|
Hi Paul,
If the guidestar is locked on and it looks like it's tracking ok (+/- 2 error on K3) then they other things that can introduce drift error are...
1. Differential flexure. This is when the movement of the mount causes the guidescope the "flex" relative to the imaging scope. Guide guidescope mounting is essential.
2. SCT mirror flop. As the scope moves the SCT mirror can "flop" around a bit causing the imaging image to "move" relative to the guidescope. I wouldn't imagine this is you problem with the new Meade 8". You can get a kit that will lock the mirror. This is ok so long as you an external focusser (eg crayford JMI like you have).
3. Poor polar alignment. This will cause field rotation errors. It's easy to spot as you will notce each Raw is rotated by the same amount each time. Polar alignement really does need to be spot on for astrophotography even with auto-guiding.
4. Too short f/ratio on guide scope. You should be ok here though, but perhaps try a barlow in the guidescope & see if that helpds
You probably know all this anyway! Welcome the joyful world of astrophotography.
|