QHY8 reprise

In a previous post, I wrote about the trouble I had with my QHY8.

So, I spent a bit of time fiddling with the QHY8 getting the CCD square to the front plate. I adjusted the rear screws and was able to get the CCD square according to my measurements. But no matter how I changed the tension, I couldn't see any difference in sample images - there was still frame-wide "coma" aligned with the CCD.

At first, I was making small adjustments to the height of the corners of the CCD - 0.2mm max. I decided to make gross movements instead, and didn't see any change in the test images. Aha! Something else is going on. It turned out to be "tearing" in the image introduced by software. The QHY8 is supported with a custom driver under Nebulosity on the Mac. Unfortunately, these seem to have some problems. After trying Nebulosity under Windows with the official QHY drivers, I finally got a very nice test image with a flat field. Nothing is perfect though, I have to reinstall the drivers frequently.

When playing around with the CCD alignment, I noticed that the cold finger the CCD is on is levered on one side. This is the side with one spacer on top of a component. I took out the screw I previously put on the right hand side, straightened the spacer and put it on the right hand side. When I reassembled the CCD, the CCD was pretty much perfectly aligned!

If the clouds of the past two months clear, hopefully I will get some imaging done with the QHY8.