View Single Post
  #56  
Old 22-04-2011, 01:22 PM
richardo's Avatar
richardo (Rich)
Love reflection Nebs !

richardo is offline
 
Join Date: Aug 2006
Location: Streaky Bay
Posts: 1,070
Hi Paul, just to jump in here,
if you're getting 2-3min unguided, and wow, through the F9 VC200L 1800FL, and you've checked all your flexure issues (like chasing the white rabbit), it still could be the VC's tube flexing??.. slight mirror movement.. fine line to over tightening those mirror clips and not having them tight enough..I know this scope.. and these were issues I found.

If not, perhaps you must be over correcting on your guiding. If using 1 sec exposures for guiding, this would be too much intervention by the guider if your unguided is this good. Too much correction will tend to be chasing the seeing, and or the small amount of movement in the setup.
Rule of thumb I've found, use 10%(or there about) of what you can do unguided. Try 3- 6 sec guider exposures.... see how this goes.. try reducing the aggressiveness of the corrections... watch the error graph in Maxim.. it will tell you if your over correcting, just mess with aggressiveness setting and watch the graph when you try different settings.. reset your peak values and see if things get better.
Maxim works very well for guiding and you have options to refine.

I think you'll find things will be better with longer guider exposures this way the mount will be doing the work and the guider will intervene periodically.

It's all experimental stuff with guiding and chasing down flexure.. there are fixes for the VC200L and it's mirror movement (ok for back in the days of just visual observing)... removing the top 'L' of the clips and just use silicone to hold the mirror in by the sides (or even a mirror sling). Also using good quality rings to hold the tube to the mount rather than the poxy attachment plate on its bottom.

Anyway, hope some of this may help.

Cheers
Rich
Reply With Quote