Sunday, September 21, 2014

Sirui R2004 Tripod for Astronomy

I was looking for a lightweight tripod that would fit in carry-on baggage and be useful for my Star Adventurer.  The Sirui R2004 tripod seemed like the perfect fit: it is 520mm collapsed (will fit diagonally into a carry-on suitcase), weighs about 1.8kg, and is rated for 15kg.

It also only costs S$85 ($68 US) which is mind-bogglingly cheap.

All of the Sirui 2-series tripods (R2xxx, N2xxx, T2xxx) have 28mm thick legs, only differing in the number of leg segments, whether one leg can be detached to form a monopod, and the material of the legs - aluminium or carbon fibre.  The R2004 is the most basic model, and hence the cheapest.

As payload I used a Sky Watcher Star Adventurer, APM Lomo 80mm apochromatic triplet in a William Optics tube, 2" Televue diagonal, and a 4mm Vixen LV eyepiece giving 120X magnification.  The total weight of all this is 8 kg, well below the alleged 15 kg capacity of the Sirui tripod.

The long and the short of it: at 120X, it takes a mind-boggling 8 seconds for vibrations to damp out after touching the focuser. Hence this tripod is wholly incapable of carrying the mentioned load.

As a control, I used the short aluminium tripod from a Vixen Polaris; this has the benefit of much larger legs, is much shorter, and has a tray to reinforce the legs.  With this tripod and the same mount and telescope, damping time is reduced to 4 seconds, which in my opinion is still excessive.

In short, the Star Adventurer is overloaded with the Lomo 80mm, and the Sirui tripod is also overloaded with an 8 kg load. Of course 120X is equivalent to 6000mm focal length.  So the Sirui tripod and Star Adventurer may still prove useful for astrophotography.  But as a visual setup for planetary, this combination is unusable.

No comments: