First experience of imaging with a mount pillar

[Stub Mandrel]

No I hadn't, but I thought I would try my 'new' one last night in the hope of a few extra minutes as Saturn transited a gap about an hour wide between trees and roof...

It was obvious  that the three allen screws would let me remove the top to attach the mount and it would make sense to fit pillar to tripod then mount to pillar. First worry was - how can I slack off the mount screw to polar align.

All became clear on removing the top, a great big thrust ball bearing, result! Someone has obviously thought this through!

In use? Well if you stick a 150PL on a HEQ5 with tripod legs fully extended and a pillar... its very high up! This makes things like swapping cameras and focusing 'interesting', you also need lengthy cables and to position everything carefully.

The big challenge is looking through the finder... I started on M57 while waiting for Saturn to appear. Syncing up on Vega, which was nearly straight up, I had to stand on a chair and lean forward over the mount. For Saturn, which needs to be spot on in the finder with an effective focal length of 3600mm and a tiny sensor, the scope was nearly horizontal. This was actually harder, as I couldn't fit a chair  close in to the tripod and it would be a bit too high. In the end I balanced on my leisure battery with my left hand behind me and a finger just touching the tripod, more for a reference to steady myself by in the dark than an actual support!

How wobbly is such a setup? Well without the pillar it's pretty solid. With it I noticed that walking round or touching the setup would cause a small circular vibration that would fade away in a few seconds. I was watching the guide graph (when on M57) and I was able to play with the aggression settings and got the RMS error down to 0.60" in both axes with a total of 0.80" which I was well happy with. It was noticeable that the one time there was a gust of wind, the graph showed a peak deflection, not huge at all but enough to see a small peak outside the 'normal' range.

 

So, will I use the pillar again? Probably in three circumstances:

1. When it improves my view by letting me peep over nearby obstructions or to locate the mount in a better position (I can polar align closer to the Evil Trees).
2. To image things near the zenith, allowing a newt to point nearly straight up, but with the tripod legs shortened for stability and convenience.
3. With my 700mm frac or small Mak to allow a better viewing position.

I suspect No. 2 will be the most useful of these.