First of all, what sort of mount are you using?? Good gearing and worm with little PE is essential.
A Vixen Sphinx - a bit better than the GPD s othey say...
Next you have to be pretty well spot with your polar alignment. Drift alignment is the only way.... guiding at these fL's is super critical for success. Many people think because their auto guiding, rough enough will be good enough... wrong!
Yup - I use WCS to get this close
Software is also an issue.... I've used Astroart and Maxim because their guide sub exposures are at a sub pixel level and it is what's needed at these critical levels imo..... not like the freebees available on the net, you don't get all the program flexibility where compensating for your mount type and drive speeds are available, heaps of other stuff as well etc. I tried many availably at the time when I was working through these issues.
Think you have something here, seem my other post.
Secondly, how are you fixing your guide scope to the mount.
DON'T fix it to the VC200L as it is!!
The tube is quite flimsy. Even if you have a rail from the top of the primary and secondary housing, this will still make the tube flex.... maybe not when you are imaging with the scope perfectly upright (90*), but when it's starting to get on its side, (90*+/-) it will be pulled out of shape and warp.
Hmm, I have an ADM rail connected to the front and rear housings - perhaps not perfect but if I go for rings and plates I will exceed the capacity of the mount. I do not think this is the issue at the moment ($$$ = denial)
Also the stock (native) dovetail rail that is used to fix the scope to the mount is very inadequate for such critical imaging purposes. Just look at it and think about it.... grab your scope and put some pressure on the tube, watch it flex... only has to be a little, that's enough to spoil any guiding at this FL.
I do not think I have got to the flexure issue yet (I am sure there is some it is just I have not got the precision to notice it yet!) - the reason I think that is that I can see the tracking errors in the guide logs, if it was flexure the guide logs would show nothing and I would still have out of round stars...
When I had my GPDX (long gone) all tuned in using PEC, I was able to get out to 1.5- 2min exposures @ F9, I had no dramas with any sort of flexure, triangular stars.
No PEc on the Sphinx means I can only go to 30s without guiding.
Look at his images..
http://members.inode.at/wasshuber/eq.../equipment.htm
Wow - now I have hope!
Hope this is all some good food for thought, believe me, I've been down this track that you are venturing upon!
Here's a couple of so so images I took with my VC... still had egg shape stars though!
http://www.baytop-observatory.com/cc...xies/m83f9.htm
http://www.baytop-observatory.com/cc.../ngc5128f9.htm
Wow again - makes my 5128 look like a joke - so this VC200L ain't bad is it?
Hope you have some success.
Me too! And thanks againn for the help Rich.