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> That's a cool shot. What scope is this?
Celstron 9.25" Edge HD SCT w/ Hyperstar 3 lens .. I love it!
> Your field curvature seems a bit excessive. I reckon your camera spacing on >the corrector plate is wrong.
Any field curvature is probably my polar alignment being off a tad so it shows in a 20 minute exposure.. even though guiding keeps it central. The curvator doesn't show at all on a 3second exposure.
> You can certainly collimate the hyperstar but that would be for field tilt.
The Hyperstar is colimated with it's screws so now the stars that are in focus are nice and round. Even the stars our of focus have a nice round symmetrical disc.
>The issue here is a spacing issue IMHO. Try to move the camera out or in a >bit and see if your field gets flatter. A couple of mm will go a long way. Then >take it from there.[/QUOTE]
The camera doesn't move in and out, it screws directly into the Hyperstar's 2" thread with a 2mm spacer which was required to achieve the right back focal distance.
As the focus issue is even across one side of the chip, I'm almost positive it's sagging enough to not be parallel to the optics but just unsure how to work it out of the system. I'll keep fiddling with QHY's flattening ring adapter and see if I can nail it. Thanks!
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