tag:blogger.com,1999:blog-183950162024-03-13T19:56:19.937+08:00orly going thirtyforty-ish mid-life crises (was: thirty-ish when I started this blog)orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.comBlogger55125tag:blogger.com,1999:blog-18395016.post-27175060400498141852020-04-07T05:14:00.000+08:002020-04-07T05:22:09.055+08:003D-Printed Adapter for ZWO ASI120 to Lacerta OAG and Canon 650D<div dir="ltr" style="text-align: left;" trbidi="on">
<a href="https://www.amazon.co.uk/d/Camera-Photo-Accessories/Lacerta-Off-Axis-Guider-Canon-Thread/B00UJUXAOE">Lacerta</a> makes a very low-profile off-axis guider with an M48 thread on one side, and a Canon EF bayonet on the other side. It is reasonably well-made, but the (used) one that I bought had some pretty serious grub screw markings on the guide camera pick-off tube due to over-tightening of the setscrews that hold the guide camera T-mount to the pick-off tube.<br />
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I can see why the previous owner did this: if the setscrews aren't tight, the guide camera can rotate, particularly if the guide camera's USB cable gets snagged on something.<br />
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I decided to 3D-print an adapter that would screw into the M4 threaded holes on the back of the ZWO ASI120 guide/planetary camera, and which in turn would hold the camera at the right distance to achieve focus, and bolt to the 1/4" 20tpi tripod socket on the Canon EOS650D DSLR.<br />
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It's a very simple design, and would need to be modified for any other guide camera and potentially DSLR, since the sizes are different and the focal points are also different. In this case, I'm using a William-Optics Flat6A flattener/reducer, with its native M48 interface at the rear.<br />
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The design is <a href="https://www.thingiverse.com/thing:4266360">here</a>.<br />
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An added bonus is that the 3D-printed adapter also helps to protect the guide camera and OAG from mishandling. Without the adapter/reinforcement, imaging what would happen if you dropped the DSLR: the pick-off tube on the OAG would most likely get bent out of shape.<br />
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And here are a few photos:<br />
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<a href="https://1.bp.blogspot.com/-piDM1E_SSb4/Xoubjyw-x5I/AAAAAAAASCg/RKV1xgsugJkTvfbSWZvRkPMhmCmYulhdgCLcBGAsYHQ/s1600/IMG_2660.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://1.bp.blogspot.com/-piDM1E_SSb4/Xoubjyw-x5I/AAAAAAAASCg/RKV1xgsugJkTvfbSWZvRkPMhmCmYulhdgCLcBGAsYHQ/s400/IMG_2660.JPG" width="400" /></a></div>
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<a href="https://1.bp.blogspot.com/-c41EQ3Ut-kg/XoubkGJXEgI/AAAAAAAASCk/lrgCO-9kOyIvSshEvc2l711qDikMIGwUACLcBGAsYHQ/s1600/IMG_2665.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://1.bp.blogspot.com/-c41EQ3Ut-kg/XoubkGJXEgI/AAAAAAAASCk/lrgCO-9kOyIvSshEvc2l711qDikMIGwUACLcBGAsYHQ/s400/IMG_2665.JPG" width="400" /></a></div>
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<a href="https://1.bp.blogspot.com/-wMR8L8UJ8fs/XoubkRYPESI/AAAAAAAASCo/jQzXHvfavBkeA_d7Bk8Qlg4YqVwJDYKggCLcBGAsYHQ/s1600/IMG_2668.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://1.bp.blogspot.com/-wMR8L8UJ8fs/XoubkRYPESI/AAAAAAAASCo/jQzXHvfavBkeA_d7Bk8Qlg4YqVwJDYKggCLcBGAsYHQ/s400/IMG_2668.JPG" width="400" /></a></div>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-18063203086438566452019-10-25T20:24:00.002+08:002019-11-30T11:00:39.207+08:00ProLink PIC3002WN Review<div dir="ltr" style="text-align: left;" trbidi="on">
This is a discontinued IP camera from ProLink (<a href="https://prolink2u.com/product/pic-3002wn/">https://prolink2u.com/product/pic-3002wn/</a>). There is another review <a href="https://zitseng.com/archives/16188">here</a> but otherwise not much additional information.<br />
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I bought four of these for home surveillance, but have discovered a number of shortcomings which you need to consider when buying these::<br />
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<li>the iOS client hard-resets my iPhone 7 Plus randomly, although my wife's iPhone 8 is "fairly" stable</li>
<li>only SD card and DropBox recording work, when recording to a NAS (Windows share) the recording randomly stops. Dropbox requires a paid Dropbox account since the number of files is quite large, and you would also need a lot of bandwidth; a day of recording is about 3GB</li>
<li>there is no FTP recording, contradicting the review linked above</li>
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<li>the cameras sometimes randomly lose their recording settings</li>
<li>there are days and days with no available recordings, because the cameras stop recording after a couple days; therefore you have to power-cycle them every few days</li>
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These cameras are cheap, and in principle have a lot of features. The video quality is reasonably OK, the IR mode works fine, but unless you use the SD card or DropBox recording, the "added" features are unreliable. And even if using SD card or DropBox, you have to reboot them every couple days otherwise they stop recording entirely.</div>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-61869051614750338402019-05-03T02:25:00.001+08:002019-05-03T13:09:45.577+08:0050mm on Full Frame Test<div dir="ltr" style="text-align: left;" trbidi="on">
This is a contrived test of center and corner sharpness of various 50mm lenses, SLR and rangefinder. I decided to compare the performance of my 1938 Leitz Summar before selling it. The test was fairly simple: I took two pictures of a Schneider wooden cuckoo clock, one at the center of the frame, and one at the edge (but not corner). All photos were taken on a Sony A7-II, with IBIS enabled, and manual focus using the zoom-in button. Distance was about 3 meters (typical portrait or half-body distance) and all lenses were wide-open to maximize aberrations.<br />
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Here's the clock face at the center of the image (rotated 90 degrees for convenience):<br />
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<a href="https://2.bp.blogspot.com/-U6Znb_PekgA/XMszdMrtUCI/AAAAAAAARik/O7lGH4gjjvsaR8WqfhQsO_mRCTnou3yvACLcBGAs/s1600/center.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="331" data-original-width="1600" height="132" src="https://2.bp.blogspot.com/-U6Znb_PekgA/XMszdMrtUCI/AAAAAAAARik/O7lGH4gjjvsaR8WqfhQsO_mRCTnou3yvACLcBGAs/s640/center.JPG" width="640" /></a></div>
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And here is the same clock face at the edge of the image (also rotated 90 degrees):<br />
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<a href="https://1.bp.blogspot.com/-dA6eg54KFbA/XMszeH5CzyI/AAAAAAAARio/tRsT6i-n2wQjXatJCYfOFhTk1t7oE1uvgCLcBGAs/s1600/edge.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="350" data-original-width="1600" height="140" src="https://1.bp.blogspot.com/-dA6eg54KFbA/XMszeH5CzyI/AAAAAAAARio/tRsT6i-n2wQjXatJCYfOFhTk1t7oE1uvgCLcBGAs/s640/edge.JPG" width="640" /></a></div>
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And here are the center images:<br />
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<a href="https://1.bp.blogspot.com/-IpvMSLbcO8w/XMszdEGjleI/AAAAAAAARj4/GDDt9qDxrtUTR0hIT4ofqww_lYoRXiBMgCEwYBhgL/s1600/canon50ltm-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://1.bp.blogspot.com/-IpvMSLbcO8w/XMszdEGjleI/AAAAAAAARj4/GDDt9qDxrtUTR0hIT4ofqww_lYoRXiBMgCEwYBhgL/s320/canon50ltm-2.JPG" width="320" /></a></div>
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Canon 50mm f/1.8 LTM</div>
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<a href="https://3.bp.blogspot.com/-xoGqbhwbvDE/XMszeb3dLeI/AAAAAAAARkI/B2mkvnOs36QMTCcEvq7tiSyJ3dLYUpZbACEwYBhgL/s1600/i61-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://3.bp.blogspot.com/-xoGqbhwbvDE/XMszeb3dLeI/AAAAAAAARkI/B2mkvnOs36QMTCcEvq7tiSyJ3dLYUpZbACEwYBhgL/s320/i61-2.JPG" width="320" /></a></div>
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Industar-61LZ 55mm f/2.8</div>
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<a href="https://1.bp.blogspot.com/-8Gr4ObbkPMU/XMsze-vutNI/AAAAAAAARkM/ntmhpuy4g_AG5Sp3Xqze31N0C7TVqTZVwCEwYBhgL/s1600/j3-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://1.bp.blogspot.com/-8Gr4ObbkPMU/XMsze-vutNI/AAAAAAAARkM/ntmhpuy4g_AG5Sp3Xqze31N0C7TVqTZVwCEwYBhgL/s320/j3-2.JPG" width="320" /></a></div>
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Jupiter-3 50mm f/1.5 Sonnar copy</div>
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<a href="https://2.bp.blogspot.com/-4DqPCw53VRM/XMszflaXrXI/AAAAAAAARkA/Zx9RTZd36osOh4BOx2LcMQKbGFnIxxlxwCEwYBhgL/s1600/j8-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://2.bp.blogspot.com/-4DqPCw53VRM/XMszflaXrXI/AAAAAAAARkA/Zx9RTZd36osOh4BOx2LcMQKbGFnIxxlxwCEwYBhgL/s320/j8-2.JPG" width="320" /></a></div>
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Jupiter-8 50mm f/2 Sonnar copy</div>
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<a href="https://2.bp.blogspot.com/-zPl3AwRO1xg/XMszf-_mnMI/AAAAAAAARkI/LqIQHrSt2Coy7OSBwqMmZJeFb5D_HG34QCEwYBhgL/s1600/pancolar-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://2.bp.blogspot.com/-zPl3AwRO1xg/XMszf-_mnMI/AAAAAAAARkI/LqIQHrSt2Coy7OSBwqMmZJeFb5D_HG34QCEwYBhgL/s320/pancolar-2.JPG" width="320" /></a></div>
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Carl Zeiss Jena Pancolar 50mm f/1.8</div>
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<a href="https://1.bp.blogspot.com/-aVS9gHzVOgs/XMszgd6RU-I/AAAAAAAARkM/kugvy53zR2829b0tOe1-IU2czFqjJsTTwCEwYBhgL/s1600/planar-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://1.bp.blogspot.com/-aVS9gHzVOgs/XMszgd6RU-I/AAAAAAAARkM/kugvy53zR2829b0tOe1-IU2czFqjJsTTwCEwYBhgL/s320/planar-2.JPG" width="320" /></a></div>
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Contax Carl Zeiss Planar 50mm f/1.7</div>
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<a href="https://3.bp.blogspot.com/-yA7Ui3uF8sU/XMszhWcdWiI/AAAAAAAARkM/sb7VxTY8_i0Os5a4w_xNFhyPzpJUlNc8ACEwYBhgL/s1600/stm50-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://3.bp.blogspot.com/-yA7Ui3uF8sU/XMszhWcdWiI/AAAAAAAARkM/sb7VxTY8_i0Os5a4w_xNFhyPzpJUlNc8ACEwYBhgL/s320/stm50-2.JPG" width="320" /></a></div>
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Canon 50mm f/1.8 STM</div>
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<a href="https://2.bp.blogspot.com/-BHrTCWUk-K8/XMsziKMPvHI/AAAAAAAARkE/slVcCx0p9n4jXgdmyif3NNHK6HYCwWwMQCEwYBhgL/s1600/summar2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://2.bp.blogspot.com/-BHrTCWUk-K8/XMsziKMPvHI/AAAAAAAARkE/slVcCx0p9n4jXgdmyif3NNHK6HYCwWwMQCEwYBhgL/s320/summar2.JPG" width="320" /></a></div>
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Ernst Leitz Wetzlar 50mm f/2 Summar (1938)</div>
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<a href="https://3.bp.blogspot.com/-v8-aGhEJiLg/XMszjXKV9yI/AAAAAAAARkM/QbW_etnhQ1kY76YdffOuMH1hHXgCw43CwCEwYBhgL/s1600/tak55-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://3.bp.blogspot.com/-v8-aGhEJiLg/XMszjXKV9yI/AAAAAAAARkM/QbW_etnhQ1kY76YdffOuMH1hHXgCw43CwCEwYBhgL/s320/tak55-2.JPG" width="320" /></a></div>
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Pentax Super-Takumar 55mm f/1.8</div>
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<a href="https://1.bp.blogspot.com/-zuAMKFG_8bA/XMszilhudDI/AAAAAAAARkE/9ZsNoHWw2gUWgudY3udxZRKZxDiGSHMYQCEwYBhgL/s1600/tak5014-2.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://1.bp.blogspot.com/-zuAMKFG_8bA/XMszilhudDI/AAAAAAAARkE/9ZsNoHWw2gUWgudY3udxZRKZxDiGSHMYQCEwYBhgL/s320/tak5014-2.JPG" width="320" /></a></div>
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Pentax Super-Takumar 50mm f/1.4 (7-element)</div>
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And the edge images:</div>
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<a href="https://4.bp.blogspot.com/-iaz0OnwBlEs/XMszdOWAq0I/AAAAAAAARj8/TfbZn8Lfg8goXdIfxsUWIViYVjDmRW58wCEwYBhgL/s1600/canon50ltm-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://4.bp.blogspot.com/-iaz0OnwBlEs/XMszdOWAq0I/AAAAAAAARj8/TfbZn8Lfg8goXdIfxsUWIViYVjDmRW58wCEwYBhgL/s320/canon50ltm-1.JPG" width="320" /></a></div>
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Canon 50mm f/1.8 LTM</div>
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<a href="https://3.bp.blogspot.com/-T-6fkZForbU/XMszeNA6vyI/AAAAAAAARj0/MJ469lUVw7A0icJwUmBC4LThyDBerj2vgCEwYBhgL/s1600/i61-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://3.bp.blogspot.com/-T-6fkZForbU/XMszeNA6vyI/AAAAAAAARj0/MJ469lUVw7A0icJwUmBC4LThyDBerj2vgCEwYBhgL/s320/i61-1.JPG" width="320" /></a></div>
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Industar-61LZ 55mm f/2.8</div>
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<a href="https://3.bp.blogspot.com/-WsL1ocydngE/XMsze1xylyI/AAAAAAAARkM/K7DcjQqcmxs0Oq_e9D__XktsSZEtVHLwwCEwYBhgL/s1600/j3-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://3.bp.blogspot.com/-WsL1ocydngE/XMsze1xylyI/AAAAAAAARkM/K7DcjQqcmxs0Oq_e9D__XktsSZEtVHLwwCEwYBhgL/s320/j3-1.JPG" width="320" /></a></div>
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Jupiter-3 50mm f/1.5 Sonnar copy</div>
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<a href="https://3.bp.blogspot.com/-c2p6JEUmObc/XMszfNQKHGI/AAAAAAAARj4/2wkrWrgDGWsbCsCgK8xewANJI2oLLe4pQCEwYBhgL/s1600/j8-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://3.bp.blogspot.com/-c2p6JEUmObc/XMszfNQKHGI/AAAAAAAARj4/2wkrWrgDGWsbCsCgK8xewANJI2oLLe4pQCEwYBhgL/s320/j8-1.JPG" width="320" /></a></div>
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Jupiter-8 50mm f/2 Sonnar copy</div>
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<a href="https://2.bp.blogspot.com/-Lh8N4WVX1X0/XMszfyy9NHI/AAAAAAAARj4/cLbbjmwlZgk82ghDU7pFcIfDVkMmDvk-ACEwYBhgL/s1600/pancolar-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://2.bp.blogspot.com/-Lh8N4WVX1X0/XMszfyy9NHI/AAAAAAAARj4/cLbbjmwlZgk82ghDU7pFcIfDVkMmDvk-ACEwYBhgL/s320/pancolar-1.JPG" width="320" /></a></div>
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Carl Zeiss Jena Pancolar 50mm f/1.8</div>
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<a href="https://4.bp.blogspot.com/-CkFAq6JQ7C0/XMszgaSj8BI/AAAAAAAARj8/WB9gsKkP0h0YK63Rr23ya1x1musk7JS8wCEwYBhgL/s1600/planar-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://4.bp.blogspot.com/-CkFAq6JQ7C0/XMszgaSj8BI/AAAAAAAARj8/WB9gsKkP0h0YK63Rr23ya1x1musk7JS8wCEwYBhgL/s320/planar-1.JPG" width="320" /></a></div>
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Contax Carl Zeiss Planar 50mm f/1.7</div>
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<a href="https://3.bp.blogspot.com/-58lTRQAYuo0/XMszgpoxWzI/AAAAAAAARkI/siXvKZHWk5ovB3nk81JBYNAHGBlb4VyyACEwYBhgL/s1600/stm50-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://3.bp.blogspot.com/-58lTRQAYuo0/XMszgpoxWzI/AAAAAAAARkI/siXvKZHWk5ovB3nk81JBYNAHGBlb4VyyACEwYBhgL/s320/stm50-1.JPG" width="320" /></a></div>
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Canon 50mm f/1.8 STM</div>
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<a href="https://4.bp.blogspot.com/-2JxG4QnmbpA/XMszh7beDdI/AAAAAAAARkA/f8WvN8-yewwGGc4ql5mIMWmzhN5NtO8dgCEwYBhgL/s1600/summar1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://4.bp.blogspot.com/-2JxG4QnmbpA/XMszh7beDdI/AAAAAAAARkA/f8WvN8-yewwGGc4ql5mIMWmzhN5NtO8dgCEwYBhgL/s320/summar1.JPG" width="320" /></a></div>
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Ernst Leitz Wetzlar 50mm f/2 Summar (1938)</div>
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<a href="https://1.bp.blogspot.com/-NJaMU2s6FFY/XMszi-xc-YI/AAAAAAAARkI/fhn70lJmNUE-or88M86e_ZMzoKTSfMlCgCEwYBhgL/s1600/tak55-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://1.bp.blogspot.com/-NJaMU2s6FFY/XMszi-xc-YI/AAAAAAAARkI/fhn70lJmNUE-or88M86e_ZMzoKTSfMlCgCEwYBhgL/s320/tak55-1.JPG" width="320" /></a></div>
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Pentax Super-Takumar 55mm f/1.8</div>
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<br /></div>
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<a href="https://2.bp.blogspot.com/-sS9JUCufkKA/XMsziTIsK_I/AAAAAAAARkI/YBLFawhRQkMsBpBMkOrDjUa8w6CeWE0_gCEwYBhgL/s1600/tak5014-1.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="320" src="https://2.bp.blogspot.com/-sS9JUCufkKA/XMsziTIsK_I/AAAAAAAARkI/YBLFawhRQkMsBpBMkOrDjUa8w6CeWE0_gCEwYBhgL/s320/tak5014-1.JPG" width="320" /></a></div>
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Pentax Super-Takumar 50mm f/1.4 (7-element)</div>
<br /></div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-61107961020543497772019-04-09T09:32:00.001+08:002019-05-03T13:09:22.064+08:003D-Printed Finder Guider<div dir="ltr" style="text-align: left;" trbidi="on">
This is a 3D-printed finder guider that I built from a 60mm achromatic objective in a metal cell from Sheldon Faworski, a length of 2" cardboard mailing tube, and some parts 3D-printed from ABS.<br />
<br />
The 3D-printed parts include:<br />
<ul style="text-align: left;">
<li>an adapter to marry the lens in cell with the cardboard tube (with suitable tapering down that does not vignette the lens aperture)</li>
<li>an adapter with two tapped grub screws to allow a standard 1.25" nosepiece to be attached to the finder guider (an ASI120MM is attached)</li>
<li>two guide scope rings</li>
</ul>
<div>
The 2" mailing tube was cut to the exact length so that the ASI120MM only just reaches focus. The ABS parts were then epoxied to the cardboard tube.</div>
<div>
<br /></div>
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<a href="https://4.bp.blogspot.com/-bVyFnU9hs6g/XKv1jhanURI/AAAAAAAARfU/ELTnDQvfvpA28_0ZmUpqvdgRrAXwWzxkACLcBGAs/s1600/DSC00721.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="426" src="https://4.bp.blogspot.com/-bVyFnU9hs6g/XKv1jhanURI/AAAAAAAARfU/ELTnDQvfvpA28_0ZmUpqvdgRrAXwWzxkACLcBGAs/s640/DSC00721.JPG" width="640" /></a></div>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-72751491825792522582019-01-23T00:31:00.000+08:002019-01-23T00:31:09.753+08:00Viltrox EF-NEX IV AF Adapter on Sony A7 II Brief Impressions<div dir="ltr" style="text-align: left;" trbidi="on">
I have written about the <a href="https://orlygoingthirty.blogspot.com/2018/10/viltrox-ef-fx1-af-adapter-brief.html">Viltrox EF-FX1</a> before.<br />
<br />
TL; DR - the EF-NEX IV performs pretty much the same way as the EF-FX1, is marginally better in some cases, and worse in other cases.<br />
<br />
AF performance is by and large acceptable to mediocre, with two notable exceptions: the Canon 16-35mm f/4 L IS and 10-18mm f/4.5-5.6 IS STM <b>will not AF</b>. On the plus side, the A7 II actually manages to AF the Canon 180mm f/3.5L Macro, which the EF-FX1 was unable to. AF is quite slow and not very reliable however.<br />
<br />
The EF-NEX IV also manages to report the focal length properly (which the EF-FX1 could not), and it can detect APS-C lenses and automatically crop (I was unable to get the "tunnel view" with the 10-18mm IS STM).</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-70984914100358568132018-12-15T02:13:00.000+08:002018-12-15T02:20:12.952+08:00Quick Test: Canon 300mm f/4 L (non-IS) for astrophotography<div dir="ltr" style="text-align: left;" trbidi="on">
The Canon 300mm f/4 L (non-IS) from the 1990's is one of Canon's discontinued, older and slower telephoto lenses. It does have UD glass. Because I already had the artificial star set up, I decided to see what star shapes look like off-axis on a Canon EOS 6D full-frame body.<br />
<br />
Note that this is a contrived test using a 50 micron artificial star, 8m away (because it's cloudy).<br />
<br />
And here it is:<br />
<br />
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<a href="https://1.bp.blogspot.com/-UhDzWY3aZlU/XBPxvHInV5I/AAAAAAAARZI/FeJN0DV51k0QUg54mFXo4G6BitV5K_vswCLcBGAs/s1600/Screen%2BShot%2B2018-12-15%2Bat%2B02.06.58.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="710" data-original-width="644" height="320" src="https://1.bp.blogspot.com/-UhDzWY3aZlU/XBPxvHInV5I/AAAAAAAARZI/FeJN0DV51k0QUg54mFXo4G6BitV5K_vswCLcBGAs/s320/Screen%2BShot%2B2018-12-15%2Bat%2B02.06.58.png" width="290" /></a></div>
It is not bad at all.<br />
<br />
Compare to the APM Lomo 80mm f/6 Super-Apo triplet ("the best 80mm APO in the world," according to some), with the Televue TRF2008, which got <a href="https://orlygoingthirty.blogspot.com/2018/12/refractor-flattenerreducer-comparison.html">the best results</a> in my artificial star test:<br />
<br />
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<a href="https://2.bp.blogspot.com/-l3-u2QinViw/XBI_iX5m_OI/AAAAAAAARYE/BNyUfVx_GGQNSsZ7ziNA8MQBEeR779wkQCPcBGAYYCw/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.07.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="702" data-original-width="620" height="320" src="https://2.bp.blogspot.com/-l3-u2QinViw/XBI_iX5m_OI/AAAAAAAARYE/BNyUfVx_GGQNSsZ7ziNA8MQBEeR779wkQCPcBGAYYCw/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.07.png" width="282" /></a></div>
Not <i style="font-weight: bold;">too bad</i> a showing for the Canon, I must say, given that the Canon is a 300mm f/4 (75mm aperture). The Lomo is the equivalent of a 384mm f/4.8 so not too far off.<br />
<br />
Conclusion: the Canon superficially looks capable of challenging the "best 80mm APO in the world" on full frame.</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-91932508871700750322018-12-13T21:17:00.004+08:002018-12-13T21:20:40.260+08:00William-Optics New Adjustable Flattener P-FLAT6AII on AP130GTX<div dir="ltr" style="text-align: left;" trbidi="on">
I've attempted to create a general formula for spacing of the <a href="https://williamoptics.com/products/accessories/barlows-flatteners/new-adjustable-flat6a-t-mount-not-included">William-Optics New Adjustable Flattener P-FLAT6AII</a> <a href="https://orlygoingthirty.blogspot.com/2018/12/william-optics-new-adjustable-flattener.html">here</a>. I've also done some <a href="https://orlygoingthirty.blogspot.com/2018/12/refractor-flattenerreducer-comparison.html">rudimentary testing of this flattener on a Lomo 80mm f/6 triplet</a> as well. The key takeaway at the 480mm focal length is that this William Optics flattener performs better than the half-priced Orion flattener/reducer, but is marginally outperformed by the 20-year old design of the Televue TRF2008, at least in my testing with an artificial star that was quite close by, not at infinity.<br />
<br />
What about on the Astro-Physics AP130GTX, which has an 819mm focal length?<br />
<br />
Based on William-Optics' tables, the closest focal lengths are the 970mm Z126, with a 1.4mm spacing, and the 711mm Z103, with a 4.6mm spacing. Neither is particularly close to 819mm, but using my<a href="https://orlygoingthirty.blogspot.com/2018/12/william-optics-new-adjustable-flattener.html"> least-squares approximation</a> with <b style="background-color: white; font-family: Arial, Tahoma, Helvetica, FreeSans, sans-serif; font-size: 14.85px;">m=-0.014</b><span style="background-color: white; font-family: "arial" , "tahoma" , "helvetica" , "freesans" , sans-serif; font-size: 14.85px;"> </span>and<span style="background-color: white; font-family: "arial" , "tahoma" , "helvetica" , "freesans" , sans-serif; font-size: 14.85px;"> </span><b style="background-color: white; font-family: Arial, Tahoma, Helvetica, FreeSans, sans-serif; font-size: 14.85px;">b=14.855</b> a spacing of 3.4mm is obtained.<br />
<br />
However, based on my previous experience with the Lomo, where the best spacing was around 2mm shorter than indicated by the table (<b>may be caused by the artificial star not being at infinity</b>) I decided to try several spacings of the Flat6 to determine the best one.<br />
<br />
First the AP130GTX with no flattener, on the corners of a Canon EOS 6D. Performance is decent, actually: the field curvature is much less than with the Lomo 80mm.<br />
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<a href="https://1.bp.blogspot.com/-j2QrWMVSwMc/XBJa6FVvYlI/AAAAAAAARYY/YU09tarFbuI2hhmbRICqJTk6RRcPwgwZQCLcBGAs/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B21.03.51.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="698" data-original-width="626" height="320" src="https://1.bp.blogspot.com/-j2QrWMVSwMc/XBJa6FVvYlI/AAAAAAAARYY/YU09tarFbuI2hhmbRICqJTk6RRcPwgwZQCLcBGAs/s320/Screen%2BShot%2B2018-12-13%2Bat%2B21.03.51.png" width="286" /></a></div>
<br />
We do observe that there still are comet-shaped stars, although they are pretty tight.<br />
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The Televue TRF2008 did very well with the Lomo, in spite of its 20-year vintage (it was released in 1999). It does not do quite as well with the AP130GTX, however, in spite of (supposedly) being designed for 400mm - 600mm focal lengths.<br />
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<a href="https://1.bp.blogspot.com/-itOxJadrViY/XBJa6YcTtCI/AAAAAAAARYo/FvxXODwXTPo5RcyvQbS_YovuP7KAc9_dQCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B21.04.00.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="704" data-original-width="630" height="320" src="https://1.bp.blogspot.com/-itOxJadrViY/XBJa6YcTtCI/AAAAAAAARYo/FvxXODwXTPo5RcyvQbS_YovuP7KAc9_dQCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B21.04.00.png" width="286" /></a></div>
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The stars are not comatic, but they are quite eggy.<br />
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The Flat6 supposedly is best at 3.4mm spacing. Here's 3mm. It's not great. The stars are round (ish), but quite diffused compared to without the flattener. This could also be down to my technique or lack of it (that's a typo, the spacing is 3mm, not 3 meters).<br />
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<a href="https://2.bp.blogspot.com/-8g2Z8PCkfdA/XBJa6TG4rTI/AAAAAAAARYs/qCzTAdbdaPMU8gXDyYDq63-u4pkWIQlrwCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B21.04.09.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="704" data-original-width="632" height="320" src="https://2.bp.blogspot.com/-8g2Z8PCkfdA/XBJa6TG4rTI/AAAAAAAARYs/qCzTAdbdaPMU8gXDyYDq63-u4pkWIQlrwCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B21.04.09.png" width="287" /></a></div>
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I decided to try an even shorter spacing of 1.5mm which would correspond to 900mm of focal length.<br />
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<a href="https://1.bp.blogspot.com/-TRnQs_Vyjr4/XBJa6ytGGuI/AAAAAAAARYw/U1SBb0CTBDkih7u237AxKaJTig9qIuPxwCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B21.04.16.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="700" data-original-width="632" height="320" src="https://1.bp.blogspot.com/-TRnQs_Vyjr4/XBJa6ytGGuI/AAAAAAAARYw/U1SBb0CTBDkih7u237AxKaJTig9qIuPxwCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B21.04.16.png" width="288" /></a></div>
While the stars are tighter, they are less round than at 3mm, and show a bit of a comatic shape. I suspect that 3.4mm or 4mm is a better choice for spacing for the AP130GTX. But performance is still only tolerable.<br />
<br />
I guess that's why AP gets away with charging $825 for their dedicated flattener.<br />
<br /></div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-60372828601994379772018-12-13T19:34:00.002+08:002018-12-14T00:15:19.062+08:00Refractor Flattener/Reducer Comparison on Lomo 80mm f/6 Super-Apo Triplet<div dir="ltr" style="text-align: left;" trbidi="on">
Some Hong Kong amateur astronomers have <a href="http://www.astrocafe.hk/viewtopic.php?f=21&t=724">done their own testing of various flatteners</a> with the Lomo 80mm f/6 Super-Apo. Their results can be summarized as such. Note that the Televue TRF2008 performs the worst in their test (24m distance to artificial star).<br />
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<a href="https://3.bp.blogspot.com/-6uzqk1978TQ/XBKFa6hzEWI/AAAAAAAARY4/7LLHTMWnhSAZMmA7QSi-Zce7tuSe_wL-QCLcBGAs/s1600/APM%2BLOMO%2B80-480%2BFlattener%2BTest.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="600" data-original-width="600" src="https://3.bp.blogspot.com/-6uzqk1978TQ/XBKFa6hzEWI/AAAAAAAARY4/7LLHTMWnhSAZMmA7QSi-Zce7tuSe_wL-QCLcBGAs/s1600/APM%2BLOMO%2B80-480%2BFlattener%2BTest.jpg" /></a></div>
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I recently purchased the <a href="https://williamoptics.com/products/accessories/barlows-flatteners/new-adjustable-flat6a-t-mount-not-included">William Optics New Adjustable Flat6A II</a> which supposedly works with a wide variety of refractors. I've collected the recommended spacings from William Optics and <a href="https://orlygoingthirty.blogspot.com/2018/12/william-optics-new-adjustable-flattener.html">generalized it to any refractor focal length</a>.<br />
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For this test, I'm using a Lomo 80mm f/6 Super-Apo with a Russian OK4 air-spaced triplet. Due to poor weather, all testing was done indoors at about 8m distance (admittedly, quite close) and a <a href="http://www.hubbleoptics.com/artificial-stars.html">Hubble Optics 5-star artificial star</a>. I used the 50-micron (smallest) star for this test.<br />
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The test images were captured with a Canon EOS 6D, which is a full-frame sensor and therefore somewhat of a challenge for these flattener/reducers. Do note that because the test was not conducted at infinity, it is not conclusive.<br />
<br />
First, the performance of the refractor without any correction at all. We can clearly see that there is quite severe field curvature. This performance is inadequate for even casual imagers.<br />
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<a href="https://1.bp.blogspot.com/-WiJzh2JBBuA/XBI_hQQgvjI/AAAAAAAARXo/Fmw0uavqJ9crlho2uu7ER98k8OoR-R98gCLcBGAs/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.08.35.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="696" data-original-width="620" height="320" src="https://1.bp.blogspot.com/-WiJzh2JBBuA/XBI_hQQgvjI/AAAAAAAARXo/Fmw0uavqJ9crlho2uu7ER98k8OoR-R98gCLcBGAs/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.08.35.png" width="285" /></a></div>
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Compare this to the performance with the inexpensive <a href="https://www.telescope.com/Orion-08x-Focal-Reducer-for-Refractor-Telescopes/p/100310.uts">Orion 8894 0.8X reducer</a>:<br />
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<a href="https://1.bp.blogspot.com/-rkMbocg98DM/XBI_hXl3QnI/AAAAAAAARYQ/J76wsc_T4DkOPW5C0KisojKA1VHInE9GQCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.08.55.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="698" data-original-width="624" height="320" src="https://1.bp.blogspot.com/-rkMbocg98DM/XBI_hXl3QnI/AAAAAAAARYQ/J76wsc_T4DkOPW5C0KisojKA1VHInE9GQCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.08.55.png" width="286" /></a></div>
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Performance is better than without any flattener, but still not that great. Note that this is at the corners of a full-frame sensor, so on a reduced-frame camera, performance would be much better.<br />
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Now for the oldie-but-goodie <a href="http://www.televue.com/engine/TV3b_page.asp?id=71&Tab=_TRF">Televue TRF2008</a> flattener/reducer for the TV85, which is designed for 400mm - 600mm focal lengths.<br />
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<a href="https://2.bp.blogspot.com/-l3-u2QinViw/XBI_iX5m_OI/AAAAAAAARYE/AtfTNCHXyOUWeyVw_aOoS4KPbo_us6csACEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.07.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="702" data-original-width="620" height="320" src="https://2.bp.blogspot.com/-l3-u2QinViw/XBI_iX5m_OI/AAAAAAAARYE/AtfTNCHXyOUWeyVw_aOoS4KPbo_us6csACEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.07.png" width="282" /></a></div>
This is a pretty good showing, significantly better than the Orion.<br />
<br />
Now for a bad example: the Altair Astro (Long Perng) <a href="https://www.teleskop-express.de/shop/product_info.php/language/en/info/p7943_Long-Perng-2--0-6x-Reducer-and-Corrector-for-APO-Refractor-Telescopes.html">0.6X reducer/corrector,</a> which was never designed for full frame:<br />
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<a href="https://2.bp.blogspot.com/-ywEcdOBgf_s/XBI_hBfbbPI/AAAAAAAARYE/sLpdAht_gG0FCV-UYH0qLjqQIbiUEF--gCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.08.45.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="694" data-original-width="626" height="320" src="https://2.bp.blogspot.com/-ywEcdOBgf_s/XBI_hBfbbPI/AAAAAAAARYE/sLpdAht_gG0FCV-UYH0qLjqQIbiUEF--gCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.08.45.png" width="288" /></a></div>
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Suffice it to say, this is barely better than no corrector at all, however there is the 0.6X focal length reduction which may offset the ugly corner stars.<br />
<br />
According to William Optics, the GT81 with a 478mm focal length requires 7.9mm of spacing with the Flat6. Here are two attempts with an 8mm spacing:<br />
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<a href="https://2.bp.blogspot.com/-jyeBXkQlh1A/XBI_ih76W0I/AAAAAAAARYI/h80xfRldiuYb587RxSY-fVGrCTK38UYqwCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.19.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="698" data-original-width="624" height="320" src="https://2.bp.blogspot.com/-jyeBXkQlh1A/XBI_ih76W0I/AAAAAAAARYI/h80xfRldiuYb587RxSY-fVGrCTK38UYqwCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.19.png" width="286" /></a></div>
<br />
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<a href="https://4.bp.blogspot.com/-QYk9GsPYKKs/XBI_itIvh3I/AAAAAAAARYQ/QIcCY81O2lYYmM776n1BUiNrE2Kjk9URQCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.28.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="700" data-original-width="622" height="320" src="https://4.bp.blogspot.com/-QYk9GsPYKKs/XBI_itIvh3I/AAAAAAAARYQ/QIcCY81O2lYYmM776n1BUiNrE2Kjk9URQCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.28.png" width="284" /></a></div>
<br />
Neither of them are very good. Definitely worse than the TRF2008. I tried spacings of 9mm and 10mm, with even worse results. With an 11mm spacing, I could not reach focus. This was almost certainly due to the artificial star not being at infinity.<br />
<br />
Here's the same Flat6 with a 6mm spacing, which is significantly less than recommended:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-G4AzP1w0ahY/XBI_jrtyMdI/AAAAAAAARYM/zRhKjokLcNMUc0r_rCncH3Jw8am0OMntQCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.54.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="686" data-original-width="618" height="320" src="https://1.bp.blogspot.com/-G4AzP1w0ahY/XBI_jrtyMdI/AAAAAAAARYM/zRhKjokLcNMUc0r_rCncH3Jw8am0OMntQCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.54.png" width="288" /></a></div>
Performance is significantly better than at 8mm, and is <b>almost</b> though not quite as good as the TRF2008.<br />
<br />
And with 4.5mm spacing:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-8n0fsMZfHqo/XBI_jU9ocPI/AAAAAAAARYI/089EVAOJIO87NwB027JcsZQWCoxWhNsVgCEwYBhgL/s1600/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.41.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="692" data-original-width="622" height="320" src="https://2.bp.blogspot.com/-8n0fsMZfHqo/XBI_jU9ocPI/AAAAAAAARYI/089EVAOJIO87NwB027JcsZQWCoxWhNsVgCEwYBhgL/s320/Screen%2BShot%2B2018-12-13%2Bat%2B19.09.41.png" width="287" /></a></div>
Correction is almost the same as at 6mm. In general, the shorter the focal length, the more correction is required. And correction is increased by increasing the spacing. Interestingly, this Lomo 80mm f/6 triplet seems to need <b>less</b> field flattening than would normally be indicated.<br />
<br />
It is somewhat disappointing, however, that after all this drama, the Flat6 cannot surpass the 1999-era TRF2008.</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-14514753387533716552018-12-02T03:15:00.000+08:002018-12-02T03:15:04.038+08:00William-Optics New Adjustable Flattener P-FLAT6AII<div dir="ltr" style="text-align: left;" trbidi="on">
William Optics has a <a href="https://williamoptics.com/products/accessories/barlows-flatteners/new-adjustable-flat6a-t-mount-not-included">new adjustable flattener</a> with (they claim) 97% of full-frame (43mm image circle) coverage for a wide range of refractors from around 480mm focal length, up to 970mm. This is almost certainly the replacement for the old P-FLAT4.<br />
<br />
There are several other adjustable flatteners such as the Long Perng one (which is cheaper).<br />
<br />
WO publishes some suggested spacings on their web site, which I have summarized here:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-AHmY5kgbaXQ/XALcwzQt1KI/AAAAAAAARV0/75XH6oPRW3o8rOzac4kxfV2KcZjC11A3wCLcBGAs/s1600/Screen%2BShot%2B2018-12-02%2Bat%2B03.07.08.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="194" data-original-width="608" height="102" src="https://4.bp.blogspot.com/-AHmY5kgbaXQ/XALcwzQt1KI/AAAAAAAARV0/75XH6oPRW3o8rOzac4kxfV2KcZjC11A3wCLcBGAs/s320/Screen%2BShot%2B2018-12-02%2Bat%2B03.07.08.png" width="320" /></a></div>
<br />
There is what I believe to be a typo. Field curvature for refractors (whether doublets or triplets) is proportional to the focal length <b>only</b> (not the focal ratio). However we see in WO's suggested spacings that the Zenithstar 71 and Gran Turismo 71 which have basically equal focal lengths, have significantly different spacings.<br />
<br />
If we do a least-squares interpolation using WO's suggested spacings, we get the following:<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-NkdH2Sn-HaU/XALdJGUZEsI/AAAAAAAARV8/zg7CKBhtPmgrsClYyOHyCJrkgpJ5hZVTQCLcBGAs/s1600/Screen%2BShot%2B2018-12-02%2Bat%2B03.07.20.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="432" data-original-width="720" height="192" src="https://3.bp.blogspot.com/-NkdH2Sn-HaU/XALdJGUZEsI/AAAAAAAARV8/zg7CKBhtPmgrsClYyOHyCJrkgpJ5hZVTQCLcBGAs/s320/Screen%2BShot%2B2018-12-02%2Bat%2B03.07.20.png" width="320" /></a></div>
<br />
Notice that the R-squared is 0.9173 which is not very good. However if we drop the Zenithstar 71 data point and keep all the rest, we get this:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-vIhYGgB-_H4/XALdKZ5b0VI/AAAAAAAARWA/CVEkN57mKM4kZRfJSBr-EY8ozyhjrf06gCLcBGAs/s1600/Screen%2BShot%2B2018-12-02%2Bat%2B03.07.43.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="434" data-original-width="720" height="192" src="https://2.bp.blogspot.com/-vIhYGgB-_H4/XALdKZ5b0VI/AAAAAAAARWA/CVEkN57mKM4kZRfJSBr-EY8ozyhjrf06gCLcBGAs/s320/Screen%2BShot%2B2018-12-02%2Bat%2B03.07.43.png" width="320" /></a></div>
<br />
A much better fit (almost a straight line) with an R-squared of 0.9926.<br />
<br />
In summary: to determine the optimal spacing for your particular refractor, use <b>m=-0.014</b> and <b>b=14.855</b> (remember the formula, <i><b>y = mx + b</b></i>).<br />
<br />
Once I get my copy of the P-FLAT6AII, I will be able to validate if the above formula holds.</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-33798626710083969602018-10-13T06:48:00.001+08:002018-10-13T07:24:03.617+08:00Viltrox EF-FX1 AF Adapter Brief Impressions<div dir="ltr" style="text-align: left;" trbidi="on">
<h2 style="text-align: left;">
<span style="font-size: medium;">Overview</span></h2>
I have been using a <a href="https://thedigitaltrekker.com/2014/12/review-zhongyi-lens-turbo-adapters-ver-ii-for-fuji-x-mount-cameras-fx/">Mitakon Zhongyi Lens Turbo II</a> (Canon EF to Fuji X-mount) for almost a year and I'm pretty happy with it: you get "full frame" cropping, and the optical quality is <a href="https://orlygoingthirty.blogspot.com/2018/01/almost-full-frame-fuji-x-camera-lens.html">surprisingly high</a>. The only downside is that a lot of wide lenses (anything wider than 24mm actually) don't work, as their rear elements collide with the reducer's front element near infinity.<br />
<br />
I'd read about various Canon EF to Fuji X AF adapters, and the cheapest one out there is the <a href="http://www.viltrox.com/en/index.php?m=index&a=show&cid=145&id=220">Viltrox EF-FX1</a>, so I bought one off ebay for $140 (expressed-shipped from China) and got it a few days later.<br />
<br />
I will dispense with all comments about build quality, etc. Build quality is adequate, equivalent to a third-party lens. That's good enough.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-W2v7yRy2jYM/W8Ekern9YRI/AAAAAAAARQI/ob0TadH4u3ojnnUXyZ91aus3V-9zgZbnACLcBGAs/s1600/DSCF5846.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="811" data-original-width="1600" height="324" src="https://1.bp.blogspot.com/-W2v7yRy2jYM/W8Ekern9YRI/AAAAAAAARQI/ob0TadH4u3ojnnUXyZ91aus3V-9zgZbnACLcBGAs/s640/DSCF5846.JPG" width="640" /></a></div>
<br />
I originally intended to do some videos comparing the AF performance of a Fuji XT-1 with the Viltrox adapter, with my Canon 6D, but it became quickly apparent that such a comparison was useless. The long and the short of it is: the XT-1 (or XE-2, I tested both) with the Viltrox adapter and almost any Canon lens, behaves like a circa 2011-2012 mirrorless camera in terms of AF performance: it's slow, hunts a lot, and often does not find focus.<br />
<br />
There is <a href="https://fujiaddict.com/2018/10/09/new-viltrox-ef-fx1-af-adapter-for-canon-ef-ef-s-to-fuji-x-mount-works-on-fujifilm-x-t3-and-lens-testing/">a review here</a> with videos of the AF performance with a wide variety of Canon lenses, but I do not consider this very useful for several reasons:<br />
<ul style="text-align: left;">
<li>high contrast subject</li>
<li>well-lighted</li>
<li>the lenses were already "close" to good focus</li>
</ul>
<div>
Basically: the video above makes the adapter look a lot more performant than it really is. I watched that video and was impressed with the AF performance, so when I actually got the Viltrox, expectations did not match reality.<br />
<br />
My testing is much less rigorous, but I did it in a dimly-lit room with low contrast subjects. Also, I made sure to crank the lenses to their minimum focusing distance before engaging the AF. For example on the 180mm f/3.5 Macro, it takes quite a long time to motor from MFD to the correct focusing distance (i.e. this is the worst-case scenario).</div>
<br />
<h2 style="text-align: left;">
<span style="font-size: medium;">Strange Bugs and Quirks</span></h2>
<ul style="text-align: left;">
<li>The adapter forces the lens EMD to act as an "auto iris" all the time - you can actually see the lens diaphragm stopping down when you point the lens at a bright light source. This is disconcerting and may not do wonders for the lens' longevity.</li>
<li>Aperture EXIF data is mis-reported for many lenses when wide open; this does not affect the actual aperture, just the reported EXIF data. For example, the Canon 50mm f/1.8 STM wide open (at f/1.8) is recorded as f/20; the Canon 35mm f/1.4L Mk I wide-open is recorded as f/16. Stopping down to f/2.0 or f/1.6 respectively records the correct aperture value in the EXIF data. However, other lenses (I tested two zooms - the 24-85mm f/3.5-4.5 USM and the 70-200mm f/2.8L USM) do record correct aperture data even wide open.</li>
<li>Only the widest focal length EXIF data for zoom lenses is recorded in the EXIF; for example the 24-85mm always reports 24mm whatever the actual focal length, and the 70-200mm always reports 70mm.</li>
<li>On STM lenses (only tested with the 50mm), the AF/MF switch is disobeyed - MF is always possible (it's manual focus-by-wire, and the adapter always enables it). This is probably a good feature to have rather than a bug.</li>
</ul>
<div>
<h2 style="text-align: left;">
<span style="font-size: medium;"><br /></span></h2>
<h2 style="text-align: left;">
<span style="font-size: medium;">Lens AF Performance</span></h2>
</div>
<div>
So to the meat of the summary: AF performance. I tested this with a variety of lenses, and as stated above, AF performance is equivalent to a circa 2011-2012 mirrorless (well, a Panasonic GF2 because that's the mirrorless I owned in that time frame). Or perhaps a sluggish modern prosumer camera like a Canon G5X, or a 10-year old entry-level Canon DSLR (like a 350D).</div>
<div>
<ul style="text-align: left;">
<li>Canon 50mm f/1.8 STM - easily the worst-performing of the first-party lenses I tested. Unable to reach focus in many (somewhat dark) situations. Hunted a lot and slow. This same lens performs very well on a Canon 6D: moderately faster AF performance, but very accurate and doesn't hunt at all in low light.</li>
<li>Canon 35mm f/1.4L Mk 1 - focuses surprisingly fast, though not as fast as natively on the 6D and hunts.</li>
<li>Canon 85mm f/1.8 - same as the 35mm.</li>
<li>Canon 135mm f/2L - same as the 35mm.</li>
<li>Canon 180mm f/3.5L Macro - I take it back, this is the worst-performing lens with the Viltrox adapter. Gets lost more often than not, AF is pretty much useless on this lens. But this lens also has mediocre AF performance on the Canon 6D.</li>
<li>Canon 24-85mm f/3.5-4.5 - focuses quite fast (see the theme? "real" ring USM lenses perform well).</li>
<li>Canon 70-200mm f/2.8L non-IS - also focuses quite fast.</li>
<li>Canon 16-35mm f/4L IS - focuses fast, <b>and IS works</b>. I was able to get sharp photos at 35mm and 1/2 second exposure time. There was an instance where the lens got disconnected and AF stopped working (and the display showed f/0 - as if no lens was attached) but restarting the camera fixed this.</li>
<li>Sigma 50mm f/2.8 Macro (the old one that locks up your camera with Error 99) - this <b>does not</b> lock up a Fuji camera! however aperture cannot be controlled, so it only operates wide-open (on any modern Canon DSLR, this lens locks up the camera if you try to set the aperture to anything other than wide-open; on old DSLR's like the 5D, it would not lock up the camera but apertures smaller than wide-open cannot be commanded).</li>
<li>Tokina 80-400mm f/4.5-5.6 AT-X AF - <b>useless</b>. At 80mm it seems to reach focus, but at 400mm it hunts around, runs back and forth <b>past the correct focus point</b>, then indicates correct focus (double beep) even when the lens is clearly not focused.</li>
</ul>
<div>
<br /></div>
<div>
<h2 style="text-align: left;">
</h2>
<h2 style="text-align: left;">
</h2>
<h2 style="text-align: left;">
Conclusion</h2>
I would not characterize the Viltrox EF-FX1 to be a cheap parlor trick (it is on the cheap side, admittedly): on fast ring USM lenses it is actually usable, although the user experience is sub-standard.</div>
<div>
<br /></div>
<div>
If you have a large pile of Canon lenses, then this adapter is useful. I do not know if Canon lenses AF faster on say, Sony A7-class mirrorless cameras, or if the more spendy Canon-to-Fuji AF adapters focus faster. But the Viltrox is $140, which is less than the cost of the cheapest Fuji primes. So if say you want a 50mm AF prime and have the Canon lying around, it's cheaper to buy the Viltrox than the Fuji XF 50mm.</div>
</div>
<div>
<br /></div>
<div>
Some Canon lenses (well the cheap 50mm STM that I tested) don't work very well, and the AF performance of all the Canon lenses is nowhere close to a 6D, which is a 4-year old, mid-tier body. Granted the XT-1 and XE-2 are also of equally dated vintage. Maybe a more modern Fuji body would perform better, but the XT-1 and XE-2 AF swiftly with native Fuji lenses, so I don't think the problem is in the body.</div>
<div>
<br /></div>
<div>
That said, if Viltrox came out with a version of this converter <b>with a built-in reducer like the Mitakon Zhongyi</b>, I'd probably buy it.</div>
</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-30877163553687734202018-09-29T06:17:00.001+08:002018-09-29T06:43:33.886+08:00Lightweight Triplet Super-Apochromat Refractor<div dir="ltr" style="text-align: left;" trbidi="on">
The Russian Lomo 80mm f/6 and f/7.5 OK4 triplet apochromats are considered by many to be among the finest 80mm refractors in the world. However, they are also known for being built like tanks. My APM Lomo 80mm f/6 in a William-Optics tube and with a Feathertouch focuser weighs 4.26 kg (9.4 lb) all in, which is heavy for an 80mm refractor.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-9Ue77blNgIc/W66sZTD8qVI/AAAAAAAARHo/xXiqhGWP_Ici7eosxfbNdm3eT9pgIXFVACLcBGAs/s1600/DSCF5843.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1065" data-original-width="1600" height="426" src="https://4.bp.blogspot.com/-9Ue77blNgIc/W66sZTD8qVI/AAAAAAAARHo/xXiqhGWP_Ici7eosxfbNdm3eT9pgIXFVACLcBGAs/s640/DSCF5843.JPG" width="640" /></a></div>
<br />
Here we see the weight with a typical 18mm AstroTech Paradigm ED eyepiece, 2" diagonal, tube rings, and small Vixen dovetail:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-bl983Sx8dyo/W66sZS-_PYI/AAAAAAAARHs/erxFQtXN2ysccpByaj5qIixZJyeF2lClwCLcBGAs/s1600/DSCF5842.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1598" data-original-width="1600" height="638" src="https://4.bp.blogspot.com/-bl983Sx8dyo/W66sZS-_PYI/AAAAAAAARHs/erxFQtXN2ysccpByaj5qIixZJyeF2lClwCLcBGAs/s640/DSCF5842.JPG" width="640" /></a></div>
<br />
On the other hand, the modular Borg refractors are well-known for being supremely portable and lightweight. However, they have been less known for being at the pinnacle of optical performance.<br />
<br />
So I wondered, what if you could marry the best traits of the Lomo OK4 triplet and the Borg refractors?<br />
<br />
Behold - the Lomoborg:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-q-dKPQyG3TM/W66nZt1l14I/AAAAAAAARHU/9FXkW0txPpEUIS64iRb03CaIqogVnMFvACLcBGAs/s1600/DSCF5840.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1068" data-original-width="1600" height="425" src="https://1.bp.blogspot.com/-q-dKPQyG3TM/W66nZt1l14I/AAAAAAAARHU/9FXkW0txPpEUIS64iRb03CaIqogVnMFvACLcBGAs/s640/DSCF5840.JPG" width="640" /></a></div>
<br />
It is constructed from the 7803 80mm diameter x 205mm long Borg tube and the 7835 helical focuser. The tube ring is from a Takahashi FS-60. This setup was for my Borg 76ED, which has a 500mm focal length. The OTA is a little too long for the Lomo 80mm f/6 which is a 480mm focal length, so some eyepieces won't reach focus (the 18mm AstroTech Paradigm ED eyepiece barely reaches focus with a 2" diagonal, with about 2mm of in-travel left).<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-o8Ci_om9F0Y/W66nZ6iOZfI/AAAAAAAARHY/TWlSplEL9qcJTHx9irqFgXU2_CtNFEcjgCLcBGAs/s1600/DSCF5841.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1597" data-original-width="1600" height="638" src="https://3.bp.blogspot.com/-o8Ci_om9F0Y/W66nZ6iOZfI/AAAAAAAARHY/TWlSplEL9qcJTHx9irqFgXU2_CtNFEcjgCLcBGAs/s640/DSCF5841.JPG" width="640" /></a></div>
<br />
All-up weight is 2.9 kg (6.4 lb) which is a win!<br />
<br />
In comparison, the Borg OTA with the 76ED objective weighs 2.46 kg (5.4 lb) so the Lomo objective adds 1 lb of weight.<br />
<br />
The Lomo lens was adapted to the Borg tube using a 3D-printed adapter, which is secured to both the lens cell and the Borg tube using 3mm grub screws - not an ideal arrangement. For an actual production setup, the adapter would need to be made of aluminum and with threaded ends. Also, some sort of dew shield would be necessary.</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-15162773863834504682018-09-23T06:09:00.001+08:002018-09-23T06:09:23.856+08:003D Printer Use Case: Repairing a Dented Lens Filter Ring<div dir="ltr" style="text-align: left;" trbidi="on">
I dropped this ancient Schneider-Kreuznach Retina lens on the floor, dinging the filter ring:<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-jIRC1m78GvE/W6a8-ZFPuyI/AAAAAAAARGc/2VMA9wbpwywsULszmj3E7F8IVgOKamX4wCLcBGAs/s1600/DSCF5779.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1600" data-original-width="1600" height="320" src="https://4.bp.blogspot.com/-jIRC1m78GvE/W6a8-ZFPuyI/AAAAAAAARGc/2VMA9wbpwywsULszmj3E7F8IVgOKamX4wCLcBGAs/s320/DSCF5779.JPG" width="320" /></a></div>
<br />
To repair it, I 3D-printed two plastic pieces (in HIPS with 100% infill) one matching the inner diameter of the filter ring, and the other matching the outside diameter:<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/--ZPG1STmYKY/W6a8-YYDKJI/AAAAAAAARGg/5pE0eB0WZMwStQW150p899sp3Jn9ECzVACLcBGAs/s1600/DSCF5784.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="673" data-original-width="674" height="319" src="https://4.bp.blogspot.com/--ZPG1STmYKY/W6a8-YYDKJI/AAAAAAAARGg/5pE0eB0WZMwStQW150p899sp3Jn9ECzVACLcBGAs/s320/DSCF5784.JPG" width="320" /></a></div>
Some ugly use of a C-clamp (the clamp's thread managed to put some marks on the opposite side of the lens filter ring, d'oh!):<br />
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<a href="https://2.bp.blogspot.com/-H1JPRY7CpjA/W6a8-ao5SmI/AAAAAAAARGk/ELtwkAshBs8I218QOO6TTn0JARoMRfIigCLcBGAs/s1600/DSCF5785.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1410" data-original-width="1410" height="320" src="https://2.bp.blogspot.com/-H1JPRY7CpjA/W6a8-ao5SmI/AAAAAAAARGk/ELtwkAshBs8I218QOO6TTn0JARoMRfIigCLcBGAs/s320/DSCF5785.JPG" width="320" /></a></div>
And the result: leaves something to be desired, but still an improvement over the original damaged filter ring.<br />
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<a href="https://2.bp.blogspot.com/-wfUtx6wPvSE/W6a8_qaHLAI/AAAAAAAARGo/TuKtVNuDNmQIKEo4CxyAFFqlWPN_K4FlQCLcBGAs/s1600/DSCF5787.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1180" data-original-width="1181" height="319" src="https://2.bp.blogspot.com/-wfUtx6wPvSE/W6a8_qaHLAI/AAAAAAAARGo/TuKtVNuDNmQIKEo4CxyAFFqlWPN_K4FlQCLcBGAs/s320/DSCF5787.JPG" width="320" /></a></div>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-58299878207311375462018-07-29T04:55:00.001+08:002018-07-29T04:58:33.287+08:00Synta/GSO Finder Bracket for Astro-Physics AP130GTX<div dir="ltr" style="text-align: left;" trbidi="on">
If you've ever had a hankering to attach a cheap and cheerful Synta or GSO finder scope (or red dot finder) to your spendy Astro-Physics AP130GTX triplet refractor, then <a href="https://www.thingiverse.com/thing:3024220">this 3D printed design</a> is for you.<br />
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<a href="https://3.bp.blogspot.com/-lFITHhotfj0/W1zX2F56tKI/AAAAAAAARDM/P64l5hqD19QGMv2rTj7XUPWmCYdWKr9LwCLcBGAs/s1600/DSCF5472.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://3.bp.blogspot.com/-lFITHhotfj0/W1zX2F56tKI/AAAAAAAARDM/P64l5hqD19QGMv2rTj7XUPWmCYdWKr9LwCLcBGAs/s400/DSCF5472.JPG" width="400" /></a></div>
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I had forgotten (or did not want..) to buy the fancy Baader Vario finder and rings from Astro-Physics when I bought my AP130GTX. Since I had a 3D printer and some cheap no-name China red dot finders, I figured I'd design a finder bracket.<br />
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<a href="https://3.bp.blogspot.com/-naSvzOQHXK0/W1zX2F6QonI/AAAAAAAARDU/r-DBlaJ1mBYgIOLtkkoSW45dACV5oejCACLcBGAs/s1600/DSCF5471.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://3.bp.blogspot.com/-naSvzOQHXK0/W1zX2F6QonI/AAAAAAAARDU/r-DBlaJ1mBYgIOLtkkoSW45dACV5oejCACLcBGAs/s400/DSCF5471.JPG" width="400" /></a></div>
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There's a bit of a complication because the AP refractor has its finder bracket screws coming out at a 20-degree angle, and the two screw holes are quite far apart. I also did not want to secure the finder bracket with a single screw. This bracket is appropriately curved to fit the AP refractor, and the screw holes are also tilted for proper alignment.<br />
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<a href="https://2.bp.blogspot.com/-85zA-XBa3NI/W1zX2GMLNnI/AAAAAAAARDQ/gvEf_zc2oTIEWhhHhVt4NTEGzdk6C_N2ACLcBGAs/s1600/DSCF5469.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1067" data-original-width="1600" height="265" src="https://2.bp.blogspot.com/-85zA-XBa3NI/W1zX2GMLNnI/AAAAAAAARDQ/gvEf_zc2oTIEWhhHhVt4NTEGzdk6C_N2ACLcBGAs/s400/DSCF5469.JPG" width="400" /></a></div>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-12373118792580969402018-06-23T17:09:00.000+08:002018-06-23T17:09:02.960+08:00Right-Angle Finder Adapter for Takahashi Polar Scope<div dir="ltr" style="text-align: left;" trbidi="on">
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This is a Yashica/Contax right angle viewfinder, which can be obtained from ebay for under $20:</div>
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<a href="https://2.bp.blogspot.com/-DLl8u61kffQ/Wy4MIwyJUPI/AAAAAAAARBw/y6fpXDKL4_sTRjDjCMs7y_VerqhIA0DdQCLcBGAs/s1600/DSCF2518.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="213" src="https://2.bp.blogspot.com/-DLl8u61kffQ/Wy4MIwyJUPI/AAAAAAAARBw/y6fpXDKL4_sTRjDjCMs7y_VerqhIA0DdQCLcBGAs/s320/DSCF2518.JPG" width="320" /></a></div>
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<a href="https://1.bp.blogspot.com/-LvKa4Z_KhwA/Wy4MI_gYBfI/AAAAAAAARB0/N4mFLYv_bik3cu9fIc02EGVcGf_Z7UKNgCLcBGAs/s1600/DSCF2519.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="213" src="https://1.bp.blogspot.com/-LvKa4Z_KhwA/Wy4MI_gYBfI/AAAAAAAARB0/N4mFLYv_bik3cu9fIc02EGVcGf_Z7UKNgCLcBGAs/s320/DSCF2519.JPG" width="320" /></a></div>
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<a href="https://2.bp.blogspot.com/-juiGCCXNG2U/Wy4MJMctBrI/AAAAAAAARB4/2mmZ7wYtqnAmnrXRK5A6PaXWpjAOsLuRQCLcBGAs/s1600/DSCF2520.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="213" src="https://2.bp.blogspot.com/-juiGCCXNG2U/Wy4MJMctBrI/AAAAAAAARB4/2mmZ7wYtqnAmnrXRK5A6PaXWpjAOsLuRQCLcBGAs/s320/DSCF2520.JPG" width="320" /></a></div>
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I decided to 3D-print an adapter allowing this finder to be attached to a Takahashi polar scope, so when using the polar scope an observer can avoid a stiff neck. The adapter can be found <a href="https://www.thingiverse.com/thing:2974046">here</a>.<br />
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Here is the Contax right-angle viewfinder attached to the polar scope on a Takahashi Space Boy mount. The adapter has two holes that need to be tapped for M4 for the set screws. 3D printing technology isn't repeatable enough at a sub-0.5mm scale to allow a tight press-fit on both the Contax finder and the Takahashi polar scope, at least when using PLA (succeeding prints may be too loose or too tight, hence the need for the set screws).<br />
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<a href="https://2.bp.blogspot.com/-5N8EJxZuYAg/Wy4MJ4iU9KI/AAAAAAAARB8/S2Mr-e8uXCUpWaxeBV6oIWhnhufeNYdugCLcBGAs/s1600/DSCF2521.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://2.bp.blogspot.com/-5N8EJxZuYAg/Wy4MJ4iU9KI/AAAAAAAARB8/S2Mr-e8uXCUpWaxeBV6oIWhnhufeNYdugCLcBGAs/s400/DSCF2521.JPG" width="400" /></a></div>
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<a href="https://4.bp.blogspot.com/-HPZDsz-iHq0/Wy4MKOMQvtI/AAAAAAAARCA/RpvdxTD8FF8yiLj6MCXGvE7U1N-kOHHGACLcBGAs/s1600/DSCF2523.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://4.bp.blogspot.com/-HPZDsz-iHq0/Wy4MKOMQvtI/AAAAAAAARCA/RpvdxTD8FF8yiLj6MCXGvE7U1N-kOHHGACLcBGAs/s400/DSCF2523.JPG" width="400" /></a></div>
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Potentially if using ABS or HIPS it might be possible to exploit the material's flexibility for a press-fit on both the Contax finder and the polar scope eyepiece end.</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-56247833927402821112018-05-26T02:14:00.002+08:002018-05-26T02:22:35.515+08:00Takahashi EM-1S Ersatz Polar Scope<div dir="ltr" style="text-align: left;" trbidi="on">
I bought an old <a href="https://orlygoingthirty.blogspot.sg/2017/06/a-tale-of-two-taks.html">Takahashi EM-1S mount</a> from Yahoo Japan, but it did not come with a polar scope. Since this mount is 25+ years old, I was not even sure if a polar scope could be bought for it. Also, the Takahashi polar scope is expensive, and since I got the EM-1S fairly cheap (for a Takahashi..) I figured it would not be worth it to buy the current polar scope.<br />
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<a href="https://4.bp.blogspot.com/-r2IDqY3Un8g/WwhPcuO-HRI/AAAAAAAARAM/WAZnuGrRv8sr-i0ssEBH7ztgGdeSdtaGACLcBGAs/s1600/DSCF2328.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1067" height="640" src="https://4.bp.blogspot.com/-r2IDqY3Un8g/WwhPcuO-HRI/AAAAAAAARAM/WAZnuGrRv8sr-i0ssEBH7ztgGdeSdtaGACLcBGAs/s640/DSCF2328.JPG" width="425" /></a></div>
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As luck would have it, I had a Celestron 6x30 "Long Eye Relief" finder scope, and I thought it might be possible to adapt this finder scope as a primitive polar scope for the EM-1S. The outer diameter of the eyepiece portion of this finder is about 24mm, and the barrel itself is 32mm in diameter. After three attempts, I came up with <a href="https://www.thingiverse.com/thing:2930613">this design for an adapter</a>, and 3D-printed it. The finder scope is a bit of a loose fit, so I added two masking tape shims:<br />
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<a href="https://1.bp.blogspot.com/-VrCsiZC3r8g/WwhPchMueVI/AAAAAAAARAE/0EBt_SB58kwBCkHhFWnRMJY4UIKlJYamgCLcBGAs/s1600/DSCF2329.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="958" data-original-width="1600" height="380" src="https://1.bp.blogspot.com/-VrCsiZC3r8g/WwhPchMueVI/AAAAAAAARAE/0EBt_SB58kwBCkHhFWnRMJY4UIKlJYamgCLcBGAs/s640/DSCF2329.JPG" width="640" /></a></div>
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There are three 3mm diameter holes in the circumference of the adapter, which must be tapped with an M4 tap and grub screws inserted to hold the finder scope in place.<br />
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Here is the ersatz polar scope in position. The adapter is a <b>very</b> tight fit in the Takahashi mount's RA bore. A strap wrench would be needed to remove the adapter. So it is important to place the finder scope into the adapter, and secure it with the grub screws, <b>before</b> inserting the adapter into the mount's RA bore. Some whacking was necessary to get the adapter to seat (although a previous version I made did not require whacking, so it's probably down to non-repeatability at sub-mm level in the 3D printer).<br />
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<a href="https://3.bp.blogspot.com/-0NcSednor3k/WwhPckSLSAI/AAAAAAAARAI/Lm9Mr8vhnXgDF5DLyyqQl07on5_3GGWMwCLcBGAs/s1600/DSCF2330.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="426" src="https://3.bp.blogspot.com/-0NcSednor3k/WwhPckSLSAI/AAAAAAAARAI/Lm9Mr8vhnXgDF5DLyyqQl07on5_3GGWMwCLcBGAs/s640/DSCF2330.JPG" width="640" /></a></div>
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The polar scope manhole cover (cap) still threads on nicely:<br />
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<a href="https://2.bp.blogspot.com/-PsTO4bRcJH8/WwhPdQsJKrI/AAAAAAAARAQ/Q911zFmhwzMgyF4bOFd1Jb65kSyr-317gCLcBGAs/s1600/DSCF2331.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="426" src="https://2.bp.blogspot.com/-PsTO4bRcJH8/WwhPdQsJKrI/AAAAAAAARAQ/Q911zFmhwzMgyF4bOFd1Jb65kSyr-317gCLcBGAs/s640/DSCF2331.JPG" width="640" /></a></div>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-24359674932957508782018-01-06T14:27:00.001+08:002018-01-06T14:47:56.863+08:00Almost Full Frame: Fuji X Camera Lens Turbo Adapter (Ver II) from Mitakon<div dir="ltr" style="text-align: left;" trbidi="on">
I very much like the form factor and UI of the Fuji X-mount cameras: they are very much the poor man's Leica.<br />
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A challenge is that wide lenses are hard to find, due to the 1.5X crop factor, since the Fuji cameras are not full-frame. The only full-frame mirrorless cameras to date are those from Sony ($$$) and Leica ($$$$$) which aren't an option for me. One could use LTM lenses such as the 15mm Voigtländer Super-Wide Heliar in LTM, but it too is rather expensive.<br />
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I've used some LTM lenses (Leica Elmar 90mm f/4 and a bunch of Russian lenses) on the Fuji XE-2, and these are fine - but still no wide-angle lens. To get say a 28mm equivalent would require an 18mm focal length. Fuji makes a very nice native X-mount 18mm lens, but it's quite expensive. All of the Fuji lenses are expensive, even the kit lens.<br />
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I discovered the <a href="http://www.zyoptics.net/product/zhongyi-lens-turbo-adapters-for-fuji-x-mount-cameras-fx/">Mitakon Camera Lens Turbo Adapter (Ver II)</a> which is a 0.726X focal reducer. I've used reducers on telescopes; what these devices do is reduce the effective focal length of an attached lens, increasing the f-ratio in the process (since the focal length shortens, but the lens' physical front aperture does not change). Focal reducers are a great idea in theory, but they also decrease back focus. This means the focal reducers can only be used with SLR lenses (which have longer back focus than the X-mount). LTM lenses cannot be reduced (so no full-frame Leica lenses on a non-full frame camera).<br />
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A concern with focal reducers is that they may reduce image quality; after all, we are introducing another 2-3 lens elements between the original lens and the camera sensor. To test this theory, I took a known-good lens (the Canon 180mm f/3.5L Macro) and mounted it on both a Canon 6D full-frame camera, and the Fuji XE-2 with the Mitakon Camera Lens Turbo Adapter. And here are the results:<br />
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Here's the full-frame image with the Canon 6D and 180mm lens:<br />
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<a href="https://1.bp.blogspot.com/-eOgk0gImbmc/WlBo2ylzhpI/AAAAAAAAQ58/hjcQySrxI3USKypurAh_TC0cW3ebDEkKwCLcBGAs/s1600/IMG_7272.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1067" data-original-width="1600" height="425" src="https://1.bp.blogspot.com/-eOgk0gImbmc/WlBo2ylzhpI/AAAAAAAAQ58/hjcQySrxI3USKypurAh_TC0cW3ebDEkKwCLcBGAs/s640/IMG_7272.JPG" width="640" /></a></div>
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And here's the same scene with the Fuji XE-2 and Mitakon focal reducer (I literally just removed the Canon DSLR body and substituted the Fuji body, since the lens was mounted using its tripod foot to a tripod). Note the obvious vignetting in the corners, and the slightly smaller field of view. The Canon 180mm Macro with the 0.726X reduction and 1.5X APS-C crop factor is effectively a 196mm lens:<br />
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<a href="https://2.bp.blogspot.com/-su8_nrSuqfc/WlBo2sIZ5NI/AAAAAAAAQ54/Qj68aoMywkkCLisgaLGkvZYsvpke3lCiQCLcBGAs/s1600/DSCF1979.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1067" data-original-width="1600" height="425" src="https://2.bp.blogspot.com/-su8_nrSuqfc/WlBo2sIZ5NI/AAAAAAAAQ54/Qj68aoMywkkCLisgaLGkvZYsvpke3lCiQCLcBGAs/s640/DSCF1979.JPG" width="640" /></a></div>
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Here's the center of the Canon image (with the pants hanging out of the window). I took several shots with both auto-focus and manual focus using Live View, and this was the sharpest. The lens was wide-open and the shutter speed around 1/1000 second, with everything on a tripod.<br />
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<a href="https://1.bp.blogspot.com/-JWK_1o_XOio/WlBo3LZLhCI/AAAAAAAAQ6Q/G050M_R4bTMoaJF1SY8pnOhpRTVSlFT1gCEwYBhgL/s1600/canon_center.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://1.bp.blogspot.com/-JWK_1o_XOio/WlBo3LZLhCI/AAAAAAAAQ6Q/G050M_R4bTMoaJF1SY8pnOhpRTVSlFT1gCEwYBhgL/s400/canon_center.jpg" width="400" /></a></div>
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and here's the same crop with the Fuji and Mitakon adapter. <b>It actually looks sharper</b> than the Canon image (and is slightly narrow in FOV). This is the same lens, although I manually focused using the Fuji's focus-peaking feature. I think the Canon image can be sharper if I had taken a RAW image. Fuji JPEG processing really does seem better than Canon's, and the X-Trans sensor probably also helps.<br />
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<a href="https://1.bp.blogspot.com/-yqcdQu1ZZ20/WlBo3goQH9I/AAAAAAAAQ6Q/TJe6I-XdpJcXqnuiktapNs4KUxqX7TlhgCEwYBhgL/s1600/fuji_center.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://1.bp.blogspot.com/-yqcdQu1ZZ20/WlBo3goQH9I/AAAAAAAAQ6Q/TJe6I-XdpJcXqnuiktapNs4KUxqX7TlhgCEwYBhgL/s400/fuji_center.jpg" width="400" /></a></div>
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Here's the corner of the Canon image (top-left, but not the extreme corner):<br />
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<a href="https://2.bp.blogspot.com/-AaHecTmlJAQ/WlBo3dTqIJI/AAAAAAAAQ6Q/Kq0-HqrcUwsdaQlOiLKLTK_YIYleOBS4gCEwYBhgL/s1600/canon_corner.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://2.bp.blogspot.com/-AaHecTmlJAQ/WlBo3dTqIJI/AAAAAAAAQ6Q/Kq0-HqrcUwsdaQlOiLKLTK_YIYleOBS4gCEwYBhgL/s400/canon_corner.jpg" width="400" /></a></div>
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and the same from the Fuji. Note it's a bit darker and the vignetting is obvious. Sharpness seems about the same as the Canon (note that the macro lens is wide-open, since you can't stop down the aperture on a Canon EF lens if it's not attached to an EOS body):<br />
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<a href="https://4.bp.blogspot.com/-0-QbxuS8mU0/WlBo3rSTrUI/AAAAAAAAQ6Q/nZjK7DiLDVcSmiRt1Rak9NFvr1uAQKMxwCEwYBhgL/s1600/fuji_corner.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://4.bp.blogspot.com/-0-QbxuS8mU0/WlBo3rSTrUI/AAAAAAAAQ6Q/nZjK7DiLDVcSmiRt1Rak9NFvr1uAQKMxwCEwYBhgL/s400/fuji_corner.jpg" width="400" /></a></div>
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Long story short: at least on this sample of the Canon 180mm f/3.5L macro lens, the Mitakon focal reducer <b>does not obviously reduce image quality</b>, when used with a Fuji XE-2 body. I'm sure the Fuji's X-Trans sensor and JPEG processing has something to do with this. It's entirely possible that the Mitakon reduces image quality from the lens, but the Fuji's in-body processing compensates for this.<br />
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I'm not inclined to test the Canon 180mm lens "native" (with no reducer) on the Fuji body, since I don't intend to use any SLR lenses un-reduced on the Fuji body. Also, the Mitakon reducer adds a layer of protection over the Fuji sensor.<br />
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Here's the Canon lens on the Fuji body, it does look a bit ridiculous:<br />
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There's just one wrinkle with the Mitakon reducer: certain lenses don't work (they don't reach infinity with the adapter) due to projecting rear elements. Here are three Pentax screw-mount lenses that I have: the Super-Takumar 50mm f/1.4, Super-Macro-Takumar 50mm f/4, and Super-Takumar 35mm f/3.5 - and only the middle lens reaches infinity with the Mitakon reducer in place. The 50mm f/1.4 and 35mm f/3.5 have projecting rear elements that strike the Mitakon's front element (bad..) when racked to infinity:<br />
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There's a <a href="https://www.flickr.com/groups/lensturbo/discuss/72157648850760054/72157688921696644/">more complete list</a> (80+ lenses) by A. Hillyard (with a Google sheet) that enumerates both compatible and incompatible lenses.</div>
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In summary, the Mitakon Camera Lens Turbo Adapter (Ver II) looks like a good choice for "almost full frame" on Fuji X-mount cameras, so long as you are willing to live without autofocus. It is also generally quite inexpensive (US$ 150).</div>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-38658641920827971302017-11-03T19:56:00.000+08:002017-11-03T20:33:55.087+08:00Canon EOS 6D + 35mm f/1.4L vs Fuji XE-2 + 23mm f/2<div dir="ltr" style="text-align: left;" trbidi="on">
<h3 style="text-align: left;">
Introduction</h3>
I've been a Canon EOS user for almost twenty years, except for a brief foray with the earlier Pentax DSLR's (K10D and K20D) about ten years ago. My favorite camera for the past few years has been the Canon 6D full-frame, with the spectacular 16-35mm f/4L IS ultrawide zoom.<br />
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The 6D and 16-35mm f/4L IS is a large chunk of optics and electronics, and while it's the perfect travel combo, I have always been on the lookout for smaller alternatives. I did have a Panasonic GF2 five years ago (with the 14mm f/2.8 prime) and that experience nearly destroyed my opinion of mirrorless cameras.<br />
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Recently I was able to obtain a Fujifilm XE-2 (which is a circa 2013 body, but had a significant firmware upgrade in 2016) and the 23mm f/2 prime lens (equivalent to 35mm on full-frame). After overcoming the sticker shock (the Fuji lenses are almost without exception priced similar to Canon L glass) I figured it would be interesting to compare the XE-2 and the 23mm prime with the Canon equivalent - 6D with the famous 35mm f/1.4L.<br />
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I used a tripod, base ISO (100 on the 6D, 200 on the XE-2) on a sunny day. This resulted in 1/4000 second shutter on the 6D. For some reason the XE-2 also wanted 1/4000 ISO at the same aperture levels, even with higher ISO. Here's the entire image (the central and corner areas are highlighted):<br />
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<a href="https://2.bp.blogspot.com/-N4X5j1vyYdo/WfxFXo2QDwI/AAAAAAAAQ1Y/FHdEYvJ0RyIuEh4UJ8plQTy27roP0y4awCLcBGAs/s1600/XE2_23_4_annotated.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1067" data-original-width="1600" height="425" src="https://2.bp.blogspot.com/-N4X5j1vyYdo/WfxFXo2QDwI/AAAAAAAAQ1Y/FHdEYvJ0RyIuEh4UJ8plQTy27roP0y4awCLcBGAs/s640/XE2_23_4_annotated.JPG" width="640" /></a></div>
<h3 style="text-align: left;">
</h3>
<h3 style="text-align: left;">
Center Performance - Canon</h3>
I compared the Canon 35mm f/1.4L at f/2 (one step down) and f/4 (three steps down) with the Fuji 23mm at f/2 (wide-open) and f/4 (two stops down). I also threw in the Canon 16-35mm f/4L IS at 35mm and f/4 (wide-open).<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-WX3l2DxFnFc/WfxFU7JsoKI/AAAAAAAAQ1c/_z_UsVhMcWYYTP6PLakcq037keyTT82lgCEwYBhgL/s1600/6D_35_2_scaled_center.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://3.bp.blogspot.com/-WX3l2DxFnFc/WfxFU7JsoKI/AAAAAAAAQ1c/_z_UsVhMcWYYTP6PLakcq037keyTT82lgCEwYBhgL/s400/6D_35_2_scaled_center.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Canon 35mm f/1.4L at f/2 - not very sharp, low contrast, and this is one stop down!</td></tr>
</tbody></table>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-bi2h7gJfNf4/WfxFWKNz-vI/AAAAAAAAQ1c/Z9nqQ7w32VAyiHImXpm6_5JFG7DAdduCACEwYBhgL/s1600/6D_35_4_scaled_center.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://4.bp.blogspot.com/-bi2h7gJfNf4/WfxFWKNz-vI/AAAAAAAAQ1c/Z9nqQ7w32VAyiHImXpm6_5JFG7DAdduCACEwYBhgL/s400/6D_35_4_scaled_center.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Canon 35mm f/1.4L at f/4 - sharper</td></tr>
</tbody></table>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-DK0aDvRgeHw/WfxFU5ZkiZI/AAAAAAAAQ1c/YQanMnReQWYdTOxumc93YWwvmICq2NCkACEwYBhgL/s1600/6D_1635_4_scaled_center.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://2.bp.blogspot.com/-DK0aDvRgeHw/WfxFU5ZkiZI/AAAAAAAAQ1c/YQanMnReQWYdTOxumc93YWwvmICq2NCkACEwYBhgL/s400/6D_1635_4_scaled_center.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Canon 16-35mm f/4L IS at 35mm f/4 (wide-open)</td></tr>
</tbody></table>
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A few takeaways:<br />
<ul style="text-align: left;">
<li>the 35L is not sharp! no wonder the Sigma ART has soundly thrashed it</li>
<li>even the 16-35mm zoom is equal to or sharper then the 35L (at the same aperture)</li>
<li>it is possible that I have a bad copy of the 35L, since I bought it used</li>
<li>it's also possible that the 6D is mis-focusing with the 35L</li>
<li>seems the 35L's only value is for its bokeh wide-open, since the 16-35mm f/4L IS is equally sharp at f/4 and more versatile</li>
</ul>
<h3 style="text-align: left;">
</h3>
<h3 style="text-align: left;">
Center Performance - Fuji</h3>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-_Aln5Pdlx5o/WfxFW7FRtTI/AAAAAAAAQ1c/TPTGogZsTlYAz340joz03-o7Ndoc1fLQwCEwYBhgL/s1600/XE2_23_2_center.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://1.bp.blogspot.com/-_Aln5Pdlx5o/WfxFW7FRtTI/AAAAAAAAQ1c/TPTGogZsTlYAz340joz03-o7Ndoc1fLQwCEwYBhgL/s400/XE2_23_2_center.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fuji 23mm f/2 at f/2 (wide-open)</td></tr>
</tbody></table>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-lflOtilbFJs/WfxFXlAbUtI/AAAAAAAAQ1c/bfHnWffpvqwPAJIsDbcXb_w64vABLfGYACEwYBhgL/s1600/XE2_23_4_center.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://3.bp.blogspot.com/-lflOtilbFJs/WfxFXlAbUtI/AAAAAAAAQ1c/bfHnWffpvqwPAJIsDbcXb_w64vABLfGYACEwYBhgL/s400/XE2_23_4_center.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fuji 23mm f/2 at f/4 (two stops down)</td></tr>
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Maybe my eyes are fooling me, or it's that magic Fuji X-Trans sensor, but the 23mm f/2 even wide-open beats the Canon 35mm f/1.4Lstopped down to f/2, and in the center, where all lenses perform their best. Also, while the Fuji sharpens up at f/4 compared to f/2, there's not much difference (unlike the Canon, where the improvement going from f/2 and f/4 is quite obvious). I would even say that the Fuji 23mm f/2 beats the Canon ultra-wide zoom, which is a very modern design.<br />
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What about the corners?<br />
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<h3 style="text-align: left;">
Corner Performance - Canon</h3>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-ZUXdtzlSehU/WfxFV8jggPI/AAAAAAAAQ1c/oe6V1fq459g_2xsTIuWdeIuLFOsBH2fBACEwYBhgL/s1600/6D_35_2_scaled_corner.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://4.bp.blogspot.com/-ZUXdtzlSehU/WfxFV8jggPI/AAAAAAAAQ1c/oe6V1fq459g_2xsTIuWdeIuLFOsBH2fBACEwYBhgL/s400/6D_35_2_scaled_corner.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Canon 35mm f/1.4 at f/2 (one stop down) - corner</td></tr>
</tbody></table>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-AOOjboKYA6I/WfxFWTrGRjI/AAAAAAAAQ1c/er8j9zf4H-4gJcbX9my3Xx2IAX2640DMwCEwYBhgL/s1600/6D_35_4_scaled_corner.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://1.bp.blogspot.com/-AOOjboKYA6I/WfxFWTrGRjI/AAAAAAAAQ1c/er8j9zf4H-4gJcbX9my3Xx2IAX2640DMwCEwYBhgL/s400/6D_35_4_scaled_corner.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Canon 35mm f/1.4L at f/4 (three stops down) - corner</td></tr>
</tbody></table>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-X6LnVid7uvE/WfxFUzxxfUI/AAAAAAAAQ1c/tvp6RdRSlmwRdecaqHF4iIIHMhH8lJemQCEwYBhgL/s1600/6D_1635_4_scaled_corner.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://3.bp.blogspot.com/-X6LnVid7uvE/WfxFUzxxfUI/AAAAAAAAQ1c/tvp6RdRSlmwRdecaqHF4iIIHMhH8lJemQCEwYBhgL/s400/6D_1635_4_scaled_corner.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Canon 16-35mm at 35mm f/4 (wide open)</td></tr>
</tbody></table>
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The Canon 35mm f/1.4L continues to underwhelm. The 16-35mm zoom continues to amaze.<br />
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<h3 style="text-align: left;">
Corner Performance - Fuji</h3>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-yXG04b8Ad7I/WfxFWwL0roI/AAAAAAAAQ1c/2-2i5veHcXkB3D2vFb-b_qUDe7cTsze-QCEwYBhgL/s1600/XE2_23_2_corner.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://1.bp.blogspot.com/-yXG04b8Ad7I/WfxFWwL0roI/AAAAAAAAQ1c/2-2i5veHcXkB3D2vFb-b_qUDe7cTsze-QCEwYBhgL/s400/XE2_23_2_corner.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fuji 23mm f/2 at f/2 (wide open)</td></tr>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://4.bp.blogspot.com/-pI8z0pDbdDU/WfxFX5oKSXI/AAAAAAAAQ1c/czKbBzgacD8xgIyAmZXarGu9F0ChvHHCQCEwYBhgL/s1600/XE2_23_4_corner.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="800" height="300" src="https://4.bp.blogspot.com/-pI8z0pDbdDU/WfxFX5oKSXI/AAAAAAAAQ1c/czKbBzgacD8xgIyAmZXarGu9F0ChvHHCQCEwYBhgL/s400/XE2_23_4_corner.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fuji 23mm f/2 at f/4 (two stops down)</td></tr>
</tbody></table>
Again, Fuji performance is at par or better than the much larger Canon 6D and L lenses. Here closer to the corners however, the 23mm f/2 lens is visibly sharper at f/4 than wide-open. Overall, the Fuji has lower contrast in JPEG's than a Canon.<br />
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<h3 style="text-align: left;">
</h3>
<h3 style="text-align: left;">
Conclusion</h3>
The Fuji XE-2 and 23mm f/2 prime is optically equal or better than (my copy of) the Canon 35mm f/1.4L (version 1) and Canon 6D at all equivalent apertures. And check out the size comparison:<br />
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<a href="https://3.bp.blogspot.com/-fBEvbe_smNM/WfxYY9oQc1I/AAAAAAAAQ1o/hoDOBDvp1noQXRW-7-6relruFWbphvqQACLcBGAs/s1600/IMG_2013.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="963" data-original-width="1600" height="192" src="https://3.bp.blogspot.com/-fBEvbe_smNM/WfxYY9oQc1I/AAAAAAAAQ1o/hoDOBDvp1noQXRW-7-6relruFWbphvqQACLcBGAs/s320/IMG_2013.JPG" width="320" /></a></div>
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The XE-2, even if it is quite a old body, is worlds away from the Panasonic GF2 in terms of usability. It turns on in half a second, has an excellent EVF (that is very usable even in the dark), and competently auto-focuses. The main LCD can be turned off with a function button to mimic DSLR behavior. The XE-2 does not AF as fast as the 6D but for most common photographic situations, it will do. The 6D focuses much faster and more effectively when it gets really dark, but in bright light the XE 2 and Canon 6D with the 35L (a ring USM lens) are effectively neck to neck.<br />
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An important caveat: <b>all of these tests were done with JPEG</b>, not RAW. And I <b>used autofocus</b> for both bodies; it's possible that the 6D was mis-focusing with the 35L, and manual focus with Live View would fix that. But nobody would use manual focus and Live View with the 35L in real life.<br />
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Furthermore, the Canon has automatic lens correction, and this was quite obvious with the 16-35mm f/4L IS, where rectilinear distortion was minimized. I believe the XE-2 also has some form of lens correction built in.<br />
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However, I think this use case (autofocus, JPEG) is a very common one for travelers and other casual users.<br />
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I must rent the 10-24mm Fuji ultrawide! if its performance matches the Canon 16-35mm f/4L IS, then that lens with the XE-2 would make the perfect travel kit.<br />
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If there's any disappointment with the XE-2, it would be<br />
<ul style="text-align: left;">
<li>it doesn't turn on instantly like any DSLR does</li>
<li>the 23mm f/2 lens is huge (larger than a Canon 50mm f/1.8) - this is not a Summicron</li>
</ul>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-38540563942243818352017-08-19T16:44:00.001+08:002017-08-22T01:12:35.418+08:00Polar Alignment With A Bubble Level<div dir="ltr" style="text-align: left;" trbidi="on">
In low-latitude locations such as Singapore (1.3521° N) or anywhere that Polaris is not visible, polar alignment can be difficult and time-consuming to achieve. One method for doing initial alignment in altitude is to use the mount's latitude scale, or a digital level of some sort.<br />
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This method is not sufficiently accurate because the mount's latitude scale normally only has 2° increments, and digital levels (in spite of their supposed high accuracy) actually have a tiny pendulum inside which is insensitive to small angle changes and really only has a resolution of 0.5° which is 30 arc-minutes and insufficient for a good polar alignment.<br />
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Here we can see an EQ mount set to zero latitude (as indicated by the bubble level) but the digital inclinometer is claiming 0.50° angle (which can be zero'ed out, but illustrates the inaccuracy of digital inclinometers).<br />
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<a href="https://4.bp.blogspot.com/-Rpu6f7dxZYs/WZfz8K1SvnI/AAAAAAAAQzA/uC19W6vhfy8xs13UImrVq0vvUOQcfTMUQCLcBGAs/s1600/IMG_7019.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1600" height="398" src="https://4.bp.blogspot.com/-Rpu6f7dxZYs/WZfz8K1SvnI/AAAAAAAAQzA/uC19W6vhfy8xs13UImrVq0vvUOQcfTMUQCLcBGAs/s400/IMG_7019.JPG" width="400" /></a></div>
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However, we can take advantage of a bubble level that has a 45° vial (or our untrustworthy inclinometer) to achieve more accurate angle measures.<br />
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The Starrett bubble level in the photo above has an accuracy of 1mm in 1m, or about 0.045° or 2.7 arc-minutes, hence we can be reasonably sure (within 5.4 arc-minutes or 1/11 of a degree) that the mount is indeed at zero latitude.<br />
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We then take note of the position of the altitude adjustment knob:<br />
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<a href="https://1.bp.blogspot.com/-XjKDfMeYR2M/WZf1V3a0eLI/AAAAAAAAQzY/E-v1Z0tDMXIM3B98u8fwCOGbcUayBB1YgCLcBGAs/s1600/IMG_7023.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1600" height="319" src="https://1.bp.blogspot.com/-XjKDfMeYR2M/WZf1V3a0eLI/AAAAAAAAQzY/E-v1Z0tDMXIM3B98u8fwCOGbcUayBB1YgCLcBGAs/s320/IMG_7023.JPG" width="320" /></a></div>
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The next step is to keep rotating the altitude knob (counting rotations as we go) until the mount is at 45° latitude (as confirmed by our bubble level or digital inclinometer):<br />
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<a href="https://4.bp.blogspot.com/-v7PB3nJCKpQ/WZf1Up8x8ZI/AAAAAAAAQzM/gMDYwOYYzoQoRBiyoWl6E_a2VrJy1sqhgCEwYBhgL/s1600/IMG_7020.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1599" data-original-width="1600" height="319" src="https://4.bp.blogspot.com/-v7PB3nJCKpQ/WZf1Up8x8ZI/AAAAAAAAQzM/gMDYwOYYzoQoRBiyoWl6E_a2VrJy1sqhgCEwYBhgL/s320/IMG_7020.JPG" width="320" /></a></div>
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Again we have an uncertainty of 5.4 arc-minutes in this measurement; adding to the uncertainty in the zero measurement, yields a total potential error of around 11 arc-minutes or 0.2°. On the other hand, if we used the digital inclinometer to zero the mount and also measure the 45° angle, our total uncertainty is 1°.<br />
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It is obvious that the bubble level provides lower error than a digital inclinometer.<br />
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In the case of the mount pictured, it took 39.60 - 39.75 turns of the knob to reach 45° +/- 0.1° latitude; this means that every turn of the knob yields 1.1295 - 1.1338° degrees (67.77 - 68.028 arc-minutes, or an average of 67.89 arc-minutes) of altitude.<br />
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We can see that the mount's latitude scale indicates roughly 45° as well, however since we don't know if the mount and tripod are level, and the latitude scale has no vernier and only 2° increments, the latitude scale alone is insufficient for setting the latitude.<br />
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<a href="https://4.bp.blogspot.com/-n_ISSbL54CE/WZf1UkLQTjI/AAAAAAAAQzc/OWhKzb4cPi0MuRExY9kQdgN2nihhbeclACEwYBhgL/s1600/IMG_7021.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1599" data-original-width="1600" height="319" src="https://4.bp.blogspot.com/-n_ISSbL54CE/WZf1UkLQTjI/AAAAAAAAQzc/OWhKzb4cPi0MuRExY9kQdgN2nihhbeclACEwYBhgL/s320/IMG_7021.JPG" width="320" /></a></div>
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If we had used the digital inclinometer, with its systematic error of 0.5° (total 1° including uncertainty about the zero point) then over 45° +/- 0.5° every turn of the knob yields 1.119 - 1.149° (67.14 - 68.94 arc-minutes or an average of 68.04 arc-minutes) of altitude.<br />
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Most EQ mounts use a sort of tangent arm assembly to adjust the altitude; as the angle gets higher, there is an increasing error. At small angles, θ ≈ sin(θ) but as θ gets larger, the error also increases. For example, at 45° (0.785 radians), sin(45°) = 0.707, a difference of 11%.<br />
<br />
Hence, we need to reduce our calculated arc-minutes per turn by around 11% - so 68.04 arc-minutes per turn of the knob is reduced to 61 arc-minutes per turn.<br />
<br />
The Astro-Physics Mach1 has a very accurate altitude adjustment, and is spec'ed for 62 arc-minutes per rotation with 16 ridges on the altitude knob (3.875 arc-minutes per ridge); this is in very close agreement with our calculated 61 arc-minutes per turn.<br />
<br />
It is obvious that by using the 0° and 45° points as reference, we can significantly reduce the effects of systematic error in the bubble level or digital inclinometer.<br />
<br />
After resetting the mount to zero latitude (again confirming with the bubble level), we can set it to 1.3521° by rotating the knob (1.3521° * 60 / 3.875 arc-minutes) = <b>21 knob ridges</b>. If we had used our derived value of 61 arc-minutes per rotation (3.8125 arc-minutes per turn), (1.3521° * 60 / 3.8125) = <b>21 knob ridges</b> which is the same as the (known for the Mach1) setting.<br />
<br />
On the other hand, if we need to set the latitude to a higher value, say 30°, we would use the 45° angle as the reference. In the case of 30°, we would zero the mount at 45°, then lower it by 15° (which is 900 arc-minutes) which would require <b>14.5 turns of the knob</b> (14 turns and an additional 8 knob ridges).<br />
<br />
This method would allow accurate altitude alignment to within (5.4 arc-minutes error of the level) + (8 arc-minutes from the knob uncertainty) of about 13 arc-minutes (0.22°) worst-case; actual error may be half that. Such a result is good but not great, a drift alignment can achieve better accuracy. With this amount of altitude error, there is approximately 3.5 arc-seconds of drift per minute, hence an unguided exposure of 1 minute with a typical DSLR will still show round stars.<br />
<br />
In contrast, had we set the mount's latitude directly from the digital inclinometer, we could have been in error by 1° which would lead to a 15 arc-second drift in 1 minute, thus limiting maximum exposure times to around 20 seconds before star elongation would be visible.</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-17709322381003741622017-06-20T02:52:00.001+08:002017-06-22T10:18:16.321+08:00Building and Using Astrometry.Net on MacOS<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: left;">
<span style="font-family: inherit;">Why Astrometry.net on MacOS? because Macs are built to take bullets and have long battery life. Unfortunately building almost anything on MacOS is ten times as hard as doing it on Linux. There are some (old) instructions for building <a href="http://astrometry.net/">Astrometry.net</a> on MacOS <a href="http://astrometry.net/doc/build.html">here</a>. However they are dated 2012. The instructions for Homebrew work fine on Yosemite with python 2.7:</span></div>
<div style="text-align: left;">
<span style="font-family: inherit;"><br /></span></div>
<div style="height: 0px; text-align: left;">
</div>
<div style="text-align: left;">
</div>
<ul class="first last simple" style="background-color: white; font-size: 16px; margin-bottom: 10px; margin-top: 0px !important; text-align: justify;">
<li style="line-height: 20.8px; text-align: justify;"><span style="font-family: inherit;">grab <a class="reference external" href="https://developer.apple.com/xcode/" style="color: #355f7c; text-decoration-line: none;">XCode</a></span></li>
<li style="line-height: 20.8px; text-align: justify;"><span style="font-family: inherit;">grab <a class="reference external" href="https://developer.apple.com/downloads/index.action" style="color: #355f7c; text-decoration-line: none;">XCode Command-line utilities</a></span></li>
<li style="line-height: 20.8px; text-align: justify;"><span style="font-family: inherit;">grab <a class="reference external" href="http://xquartz.macosforge.org/landing/" style="color: #355f7c; text-decoration-line: none;">XQuartz</a></span></li>
<li style="line-height: 20.8px; text-align: justify;"><span style="font-family: inherit;">grab <a class="reference external" href="http://mxcl.github.com/homebrew/" style="color: #355f7c; text-decoration-line: none;">Homebrew</a></span></li>
<li style="line-height: 20.8px; text-align: justify;"><span style="font-family: inherit;">grab <a class="reference external" href="http://www.pip-installer.org/en/latest/installing.html" style="color: #355f7c; text-decoration-line: none;">pip</a></span></li>
</ul>
<br />
<div style="text-align: left;">
<span style="font-family: inherit;">However, there are some missing steps:</span></div>
<div style="text-align: left;">
</div>
<ul style="text-align: left;">
<li>you need to have index files, get them from <a href="http://broiler.astrometry.net/~dstn/4100/">http://broiler.astrometry.net/~dstn/4100/</a> (wide-field images) or <a href="http://broiler.astrometry.net/~dstn/4200/">http://broiler.astrometry.net/~dstn/4200/</a></li>
<li>Homebrew wants them in <span style="font-family: "courier new" , "courier" , monospace;">/usr/local/Cellar/astrometry-net/0.70/data</span>, your mileage will vary depending on the version of Astrometry.net that you have</li>
<li>you need to install pyfits (<span style="font-family: "courier new" , "courier" , monospace;">sudo pip install pyfits</span>)</li>
</ul>
With the above conditions met, Astrometry works fine.</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-29396873615307896732017-06-18T20:19:00.001+08:002017-06-24T10:30:04.208+08:00Takahashi EM-1S RA Drive Analysis and Southern Hemisphere Modification<div dir="ltr" style="text-align: left;" trbidi="on">
I had a look at the innards of the Takahashi EM-1S RA drive, because I wanted to see how hard it would be to convert it to center-positive. Quick answer: it's hard.<br />
<br />
A second problem was how to use the EM-1S in the Southern hemisphere. Here is the outside of the EM-1S RA drive panel. It is obvious that there is no way to switch from northern to southern hemisphere tracking:<br />
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<a href="https://2.bp.blogspot.com/-vlG9ZARKXBc/WUZtjaoZWrI/AAAAAAAAQtk/d_QEc00u9dooiYjFDkGW64el4U9DS86ggCLcBGAs/s1600/IMG_1793.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://2.bp.blogspot.com/-vlG9ZARKXBc/WUZtjaoZWrI/AAAAAAAAQtk/d_QEc00u9dooiYjFDkGW64el4U9DS86ggCLcBGAs/s400/IMG_1793.JPG" width="400" /></a></div>
<br />
Inside, we see a Sanryusha P43G stepper motor with 24 pulses per revolution and a 1:500 gearbox. This is the same motor in my EM-11 Temma2 Jr. and presumably many other Takahashi mounts.<br />
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<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-c76RHcI8RGc/WUZuo7042WI/AAAAAAAAQts/cXrcTgWEr7wUtmJazkv62hfSn9Rgeog_gCLcBGAs/s1600/IMG_1788.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="213" src="https://4.bp.blogspot.com/-c76RHcI8RGc/WUZuo7042WI/AAAAAAAAQts/cXrcTgWEr7wUtmJazkv62hfSn9Rgeog_gCLcBGAs/s320/IMG_1788.JPG" width="320" /></a></div>
<br />
The circuit is fairly simple but full of obsolete components.<br />
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<a href="https://3.bp.blogspot.com/-dLELkYnDJME/WUZtjMLapII/AAAAAAAAQtg/pxifVcZnumM9VCHFDa4cr-vb0ofSLin_wCLcBGAs/s1600/IMG_1792.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1600" height="400" src="https://3.bp.blogspot.com/-dLELkYnDJME/WUZtjMLapII/AAAAAAAAQtg/pxifVcZnumM9VCHFDa4cr-vb0ofSLin_wCLcBGAs/s400/IMG_1792.JPG" width="398" /></a></div>
<br />
We see the following IC's:<br />
<ul style="text-align: left;">
<li>IC1: OKI M5562, Google is not very helpful, but most likely this is a clock generator IC</li>
<li>IC2: Toshiba TC4013BP, dual D-type flip flop, probably the logic generator for the stepping waveform</li>
<li>IC3: TDG2004, my immediate guess was this is a variant of the ULN2004 stepper motor driver</li>
</ul>
Supposedly, there is a switch on the board to enable southern hemisphere tracking, but there is no such switch here. It's fairly apparent that in order to make this mount useful in the southern hemisphere, the wires from the motor to the ULN2004 will have to be switched around - a highly annoying chore.<br />
<br />
With some tracing, we can determine that the topmost two wires from the motor are the commons (the motor is a 6-wire unipolar with split center tap) and the other four wires are the four phases.<br />
<br />
Therefore, it should be possible to reverse the direction of rotation by swapping the four wires that go to pins 13, 14, 15, and 16 of the TDG2004.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-kQea2ihd0ts/WUaU1sWBh3I/AAAAAAAAQt8/99-RFFMiXQophjpZERt8NHsUR2zllTtCACLcBGAs/s1600/2017-06-17.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1143" data-original-width="1600" height="456" src="https://2.bp.blogspot.com/-kQea2ihd0ts/WUaU1sWBh3I/AAAAAAAAQt8/99-RFFMiXQophjpZERt8NHsUR2zllTtCACLcBGAs/s640/2017-06-17.jpg" width="640" /></a></div>
<br />
To be more specific, assuming a stepping sequence of 1-2-3-4 (where the white wire from the motor is 1, blue is 2, black is 3, and yellow is 4) the motor should run in reverse with a stepping sequence of 4-3-2-1. In other words, swap 1 and 4, and 2 and 3.<br />
<br />
To make this process simpler and avoid multiple soldering and de-soldering chores, I soldered some Berg pins to the board, and attached connectors to the motor wires. After some challenges (the #2 connection broke which prevented the motor from turning) I was able to validate that indeed, the motor now runs in reverse.<br />
<br />
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<a href="https://1.bp.blogspot.com/-Nv7TDLHaksU/WU3OVmJxMkI/AAAAAAAAQus/_Lyu7PNtoqEV5TGXy7iq7BQotCIYAs-lgCLcBGAs/s1600/IMG_1799.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="425" src="https://1.bp.blogspot.com/-Nv7TDLHaksU/WU3OVmJxMkI/AAAAAAAAQus/_Lyu7PNtoqEV5TGXy7iq7BQotCIYAs-lgCLcBGAs/s640/IMG_1799.JPG" width="640" /></a></div>
<br /></div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-56773350828585345622017-06-18T14:41:00.001+08:002017-06-18T14:43:31.454+08:00Repairing Astro-Physics GTO Hand Pad Cable<div dir="ltr" style="text-align: left;" trbidi="on">
The cable on my <a href="http://www.astro-physics.com/index.htm?products/mounts/electronics/keypad">Astro-Physics GTO hand pad</a> cable (AP part number E0190CABLE-E) had deteriorated over time. The rubber insulation had peeled and cracked, exposing the shielding and conductors underneath.<br />
<br />
I repaired it temporarily using black duct tape but the tape left a sticky residue and was pretty ugly. Astro-Physics wants $75 (plus shipping) for a replacement cable. Good to know I can buy the part, but I wanted to save some money.<br />
<br />
While at <a href="https://www.popular.com.sg/">Popular Bookstore</a> last night, I saw a kiosk with a strange Play-Doh like adhesive, <a href="https://sugru.com/">Sugru</a>. A video was playing, touting various wonderful features. The adhesive was quite expensive (S$ 19.90 for eight tiny single-use packets) but I figured it was worth a try.<br />
<br />
This adhesive <a href="https://www.amazon.com/Sugru-Moldable-Glue-Pack-8/dp/B00WW8KIRI/">can also be purchased on Amazon</a>, for $19.58 - so the price at Popular was actually lower.<br />
<br />
And.. 12 hours later. The adhesive has hardened into a somewhat-flexible silicone rubber which feels pretty tough (the red material around the handpad cable at the bottom-left of the photo below). I would say this is a qualified success!<br />
<br />
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<a href="https://4.bp.blogspot.com/-Zy1_GbBKBW0/WUYgXnxQtFI/AAAAAAAAQtA/w9M9M8qSUU8EmbgzthRh5TMU_Z0BCIUkACLcBGAs/s1600/IMG_1790.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1067" height="640" src="https://4.bp.blogspot.com/-Zy1_GbBKBW0/WUYgXnxQtFI/AAAAAAAAQtA/w9M9M8qSUU8EmbgzthRh5TMU_Z0BCIUkACLcBGAs/s640/IMG_1790.JPG" width="425" /></a></div>
<br /></div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-28064353861237523012017-06-17T15:52:00.000+08:002017-06-17T16:13:24.307+08:00A Tale of Two Taks<div dir="ltr" style="text-align: left;" trbidi="on">
I recently was able to buy a used Takahashi EM-1S from <a href="https://auctions.yahoo.co.jp/">Yahoo Japan Auctions</a>. Generally, Japanese sellers don't ship out of Japan, but <a href="http://www.fromjapan.co.jp/en/">From Japan</a> made the process much easier. There's not much in the way of buyer protection, however. More on this later.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-jOwaifD0Ygs/WUTdYp-zABI/AAAAAAAAQsE/tVVX6m3x26AXdBDud-DYrghwzTmGaKwJQCLcBGAs/s1600/IMG_6001.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1067" data-original-width="1600" height="426" src="https://1.bp.blogspot.com/-jOwaifD0Ygs/WUTdYp-zABI/AAAAAAAAQsE/tVVX6m3x26AXdBDud-DYrghwzTmGaKwJQCLcBGAs/s640/IMG_6001.JPG" width="640" /></a></div>
<br />
I already own a nice Takahashi EM-11 Temma 2 Jr. which I've <a href="http://orlygoingthirty.blogspot.sg/2015/02/takahashi-em-11-temma-2-jr-review.html">reviewed in the past</a> (the mount on the right in the above photo). It is supposed to be my travel mount (for when I travel to the Canary Islands.. someday..) but ironically I am not too keen on traveling with it because it is rather expensive and would be subject to the slings and arrows of outrageous fortune in the checked baggage.<br />
<br />
Incidentally the EM-1 (the mount on the left) has a Canon 300mm f/4 L telephoto lens on it, and the Kenko Lens2Scope adapter, which is a 10mm eyepiece (of narrow field.. I estimate 40 degrees) and erecting 45-degree prism. The Lens2Scope is useful because when traveling, you can use the camera lens as both a small telescope and for astrophotography.<br />
<br />
But I digress.<br />
<br />
I got the EM-1S for the unheard-of price (by Takahashi standards..) of around $550. Based on the serial number it is a 1991 model, about fifteen years older than my 2006 EM-11 and making it 26 years old. It did not come with a counterweight shaft or weights, but I thought that was fine since I have an extra counterweight shaft and weights.<br />
<br />
And that is where the good news ends. It arrived with a bent RA worm shaft. I tried to straighten the shaft on the RA clutch knob with a pair of pliers.. and the shaft snapped clean off. I was able to successfully straighten (more or less..) the RA worm shaft with a block of wood and some judicious whacks with a hammer. The shaft isn't perfectly straight but the worst of the RA spur gear wobbling has been taken out. I hope I didn't damage the worm with that Lizzie Borden activity..<br />
<br />
The EM-1S has a tangent arm in declination, not a full worm. Oops! and it's quite hard to turn. I cleaned and re-lubed it but the DEC slow motion still binds a bit and does not feel smooth. Also, it seems to not have ball bearings, but rather sleeve bearings (like the Vixen Super Polaris and Great Polaris of similar vintage).<br />
<br />
The worst bit is - my particular EM-1S is missing its famous Takahashi polar scope. Which is quite annoying. I do not know if I will get any satisfaction from the Yahoo Japan seller, since they stated that "only the parts shown in the photos are included" - and the photos showed the mount with its manhole polar scope cover screwed on, and no evidence of a polar scope.<br />
<br />
In any case: the manhole covers on both the EM-1S and EM-11 fit each other. I suspect the EM-11 polar scope would fit as well but I don't want to remove it and potentially ruin the alignment. They both have the 35mm dual bolts on the top (I was able to use the Berlebach dovetail clamp from the EM-11 on the EM-1S). The tripod bases are also compatible. Even more impressive, both mounts use the same Sanryusha P43G stepper motor with 24 pulses per revolution and a 1:500 gear reduction.<br />
<br />
I hear that the current small Takahashi mounts still use this model of motor. They must have a massive warehouse full of these motors somewhere.<br />
<br />
The EM-1S does seem to have a larger-diameter RA worm wheel and is a bit lighter than the EM-11. It is powered by a rather large center-negative 6V battery pack, I will check if I can power it from a USB power bank.<br />
<br />
Overall I am a bit underwhelmed. The old Tak isn't at the quality level of the new one, although admittedly it is better-built than Vixen mounts of the same age. And the lack of a polar scope peeves me - although luckily most of the time I won't actually be using the polar scope since I'm at a low latitude. I will try to see if getting a Takahashi polar scope is not out of the question cost-wise; if cost is prohibitive I will probably find someone to machine an adapter so I can use the cheap CG-4 or CG-5 polar scope in the EM-1S.<br />
<br />
Was buying the EM-1S worth it? I will give a qualified yes. P2Z, P2, and Space Boy mounts on Yahoo Japan (the mount I <b>really</b> wanted) sell for high prices (95000 JPY or $900 if you're lucky, but more typically up to $1500). I wanted a cheap Tak mount with setting circles for travel and got one. Hopefully the periodic error is low (-er than my Vixen Super Polaris) because that was my goal.</div>
orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-63146879267620557872017-05-06T17:40:00.002+08:002017-05-06T17:46:23.564+08:00Takahashi Mewlon 210 Vignetting on Full Frame<div dir="ltr" style="text-align: left;" trbidi="on">
The <a href="http://www.takahashi-europe.com/en/mewlon.specifications.php">Takahashi Mewlon 210</a> <a href="http://www.telescope-optics.net/dall_kirkham_telescope.htm">Dall-Kirkham Cassegrain</a> only has an 18mm image circle at prime focus, and 39mm with the dedicated reducer.<br />
<br />
Here are some images of daytime scenes taken with a Canon 6D full-frame DSLR.<br />
<br />
Native focal length (2415mm, f/11.5)<br />
<br />
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<a href="https://1.bp.blogspot.com/-oli88ketPH4/WQ2ZpVU7V2I/AAAAAAAAQrA/JyJ6AignEIIDl24oLi976Eam05Fyqd7tACLcB/s1600/IMG_5988.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" height="266" src="https://1.bp.blogspot.com/-oli88ketPH4/WQ2ZpVU7V2I/AAAAAAAAQrA/JyJ6AignEIIDl24oLi976Eam05Fyqd7tACLcB/s400/IMG_5988.JPG" width="400" /></a></div>
<br />
With a Televue TRF2008 0.8X reducer/flattener for the TV85 (designed for 600mm radius of curvature) (f/9.2)<br />
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<a href="https://1.bp.blogspot.com/-N8k1Mtw7Fj8/WQ2ZpjaYQsI/AAAAAAAAQrE/8igLD5yS_HIPvBdkzGv7AN95lFut52qmACLcB/s1600/IMG_5986.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" height="266" src="https://1.bp.blogspot.com/-N8k1Mtw7Fj8/WQ2ZpjaYQsI/AAAAAAAAQrE/8igLD5yS_HIPvBdkzGv7AN95lFut52qmACLcB/s400/IMG_5986.JPG" width="400" /></a></div>
<br />
and with an Altair Astro 0.6X reducer/flattener (no longer available, but also sold by some other Europe-based sellers) (f/6.9)<br />
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<a href="https://1.bp.blogspot.com/-FgRSmnng6Bc/WQ2ZpLsUS0I/AAAAAAAAQq8/edLEuWp73fklDh7u_C5q-q-qot_2IxeDwCLcB/s1600/IMG_5987.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="266" src="https://1.bp.blogspot.com/-FgRSmnng6Bc/WQ2ZpLsUS0I/AAAAAAAAQq8/edLEuWp73fklDh7u_C5q-q-qot_2IxeDwCLcB/s400/IMG_5987.JPG" width="400" /></a></div>
I will try to get some images of a large globular like Omega Centauri when I get the chance, but the illuminated field is not bad at all (an f/4 newtonian with a Paracorr has a comparable field to the Mewlon with the 0.6X reducer!)<br />
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-16213630077381319302017-05-04T03:09:00.002+08:002017-05-04T23:34:00.770+08:00Takahashi Mewlon 210 Maintenance<div dir="ltr" style="text-align: left;" trbidi="on">
I've been looking for a <a href="http://www.takahashi-europe.com/en/mewlon.specifications.php">Takahashi Mewlon 210</a> Dall-Kirkham Cassegrain since about 2010, but the new prices are pretty high and I didn't want to pay list price. I was able to find a used one (I am probably the third or fourth owner) on <a href="http://www.singastro.org/">SingAstro</a> for a pretty fair price. The downside was that it had some dings on the paint.<br />
<br />
I had some <a href="https://www.amazon.com/Rust-Oleum-203000-6-Ounce-Specialty-Appliance/dp/B000RNPGKO/">enamel repair paint</a> and some <a href="https://www.amazon.com/Touch-Paint-Camera-Ultrasonic-Lenses/dp/B00G0TL5O0">Canon touch-up paint</a> for old grey L lenses (not a perfect color match for Takahashi hardware) but they suffice for now.<br />
<br />
After a thorough cleaning (lots of black marks on the Takahashi hardware came off with the use of a rubber pencil eraser) I found several areas where there was paint loss. On the gloss-white tube, I used the enamel repair paint.<br />
<br />
Before and after:<br />
<br />
A large area of paint loss on the front of the tube:<br />
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A smaller area where the paint flaked off, also on the front of the tube:<br />
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A ding on the finder bracket, and after patching with the Canon paint:<br />
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The Mewlon also came with a Vixen dovetail, but I wanted to mount it on my Mach1 mount and did not want to buy tube rings (which cost more, and add unwanted weight). I had a <a href="https://farpointastro.com/product/dovetail-bread-board-fdbb/">short Losmandy dovetail</a> from <a href="https://farpointastro.com/">FarPoint Astro</a>, but it didn't have the holes in the right spots.<br />
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So I bolted the stock Vixen dovetail to the FarPoint dovetail and centered it so that I could use the Vixen dovetail as a drilling guide.<br />
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And after drilling. The second hole was not very well done; but it's not visible when clamped on the Losmandy saddle; and is definitely not visible at night!<br />
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Also, I found that the cheap reticle illuminator from a Seben reticle eyepiece actually fits in the reticle socket of the 50mm finder (not very well, however):<br />
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I did feel some grittiness when screwing in the illuminator plug afterwards; I think some metal came off the cheap Seben illuminator due to the not-quite-correct threading. So I probably have to buy the real Takahashi illuminator.<br />
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After maintenance, attaching the Losmandy dovetail, and mounting on the Mach1:<br />
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0tag:blogger.com,1999:blog-18395016.post-13260773875925858282017-03-26T00:35:00.001+08:002017-05-04T23:04:39.187+08:00Canon 28-105mm f/3.5-4.5 USM II<div dir="ltr" style="text-align: left;" trbidi="on">
<b><span style="font-size: large;">TL; DR - use it at f/8 and it has (almost) L-class sharpness.</span></b><br />
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Back in 2001 or 2002 this was one of the lenses I wanted. It was too steep for me and I ended up with a Sigma 28-105mm f/2.8-4 (the infamously soft and bulky lens) which I used for some time on an EOS3000N and EOS50 until it got damaged (diaphragm stuck wide-open).<br />
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Fast-forward fifteen years and I have one from KEH for about $120 in "bargain" condition.<br />
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I have two lenses that cover (parts of) the range of this 28-105mm: the 16-35mm f/4 L IS, and the 70-200mm f/2.8 L IS. I was planning to compare these lenses but it turns out that The Digital Picture already has a <a href="http://www.the-digital-picture.com/Reviews/Comparison-Tools.aspx">lens comparison service</a>. So here's the summary (so far as I can tell) on a 5D Mk III (which has the same sensor as my 6D):<br />
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Compared to the 16-35mm f/4 L IS (an $800 lens):<br />
<ul style="text-align: left;">
<li>at 28mm and f/8, the 28-105 almost matches the 16-35mm wide-open (at f/4)</li>
<li>this is also true at 35mm</li>
</ul>
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Compared to the 70-200mm f/2.8 L (a $1200 lens):</div>
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<ul style="text-align: left;">
<li>at 70mm and f/8, the 28-105 matches the 70-200mm at 70mm wide-open (at f/2.8) and at f/4, but notably the 28-105 has better corners than the 70-200 (note we are comparing f/8 to f/2.8 and f/4)</li>
<li>at 105mm and f/8, the 28-105 matches the 70-200mm at 100mm wide-open (at f/2.8) and at f/4, but the 70-200 beats the zoom in the corners even at f/2.8</li>
</ul>
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The long and the short of it: the 28-105mm can produce almost-L class sharpness so long as you stick to f/8. However, the 28-105 has one massive feature that trumps these L lenses:</div>
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It is tiny (about the same size as a 35mm f/1.4) and not much larger than the Nifty Fifty.<br />
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My wife and I have traveled a lot with the 6D and 16-35mm f/4 L IS, and it is quite a large and bulky setup, which is why we ended up also buying a Canon G5X (which has a 24-105mm equivalent lens, with IS, and a 1" sensor). The G5X is tiny, but slow (slow to auto-focus and take photos) and has an EVF instead of an optical viewfinder.<br />
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I was stuck with the 16-35mm in Monterey in October 2016 when we went whale-watching, and 35mm is much too short for whales. The 28-105mm would have been useful to have at that time: 105mm long end, f/8 is useful as there was full sun, and the 28-105mm doesn't add much weight or bulk to the camera bag.</div>
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Ultimately that's what I see the 28-105mm as: a useful adjunct to an ultra-wide L lens for travel. The 70-200mm is simply too large and bulky to be convenient when traveling. Furthermore, on a 5D Classic, I believe the gap between the 28-105mm and the L zooms would be even less.<br />
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I believe there's one reason the 28-105mm f/3.5-4.5 is unpopular and cheap, in spite of its FTM focusing, ring USM, and focusing scale: the zoom range is not very useful on reduced-frame (APS-C) DSLR's.</div>
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orly_andicohttp://www.blogger.com/profile/09177652962226123898noreply@blogger.com0