Viltrox EF-NEX IV AF Adapter on Sony A7 II Brief Impressions

I have written about the Viltrox EF-FX1 before.

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.

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 will not AF. 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.

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).

Quick Test: Canon 300mm f/4 L (non-IS) for astrophotography

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.

Note that this is a contrived test using a 50 micron artificial star, 8m away (because it's cloudy).

And here it is:

It is not bad at all.

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 the best results in my artificial star test:

Not too bad 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.

Conclusion: the Canon superficially looks capable of challenging the "best 80mm APO in the world" on full frame.

AWS Z1D, M5A (AMD EPYC) Performance Comparison

This is the time-honoured Linux kernel benchmark.

In order to prepare a stock Amazon Linux 2 installation to compile the kernel, the following packages need to be installed:

sudo yum update
sudo yum install kernel-devel
sudo yum install ncurses-devel
sudo yum install bison
sudo yum install flex
sudo yum install openssl-devel

Preparation was simply unzipping the 4.20-rc3 tarball from, running "make menuconfig" and immediately saving the config (no changes) and then make -j 4.

This was on Amazon Linux 2, with a 40GB GP2 EBS block storage volume.

AMD EPYC m5a.xlarge:

time tar zxf linux-4.20-rc3.tar.gz

real 0m6.109s
user 0m5.928s
sys 0m2.838s

And the kernel build:

time make -j 4

real 18m31.421s
user 66m52.071s
sys 5m54.968s

Intel Xeon Platinum m5.xlarge:

time tar zxf linux-4.20-rc3.tar.gz 

real 0m4.693s
user 0m4.688s
sys 0m1.767s

the kernel build:

time make -j 4

real 14m4.332s
user 49m12.569s
sys 5m44.682s

So there we have it: on a kernel compilation, one run, the Intel instance completed the kernel compilation 25% faster.

Update 13-Dec-2018. The new Z1D instance is supposed to be significantly faster than M5/C5/R5 due to sustained 4 GHz Turbo Boost on all cores.

time tar zxf linux-4.20-rc3.tar.gz 

real 0m3.648s
user 0m3.623s

sys 0m1.438s

z1d.xlarge (also 4 vCPU) is 22% faster than m5.xlarge at uncompressing the kernel.

the kernel build:

time make -j 4

real 11m25.560s
user 39m35.242s

sys 5m2.343s

also 23% faster. So it looks like for general purpose workloads (that are probably I/O bound) the Z1D only provides a 20% performance uplift.