Quote:
Originally Posted by Xeteth
I've should receive my new camera tomorrow which is a QHY16200a APS-H, with 2" LRGBHSO filters and I'm wondering about tube size and vignetting. I've tried searching for answers but have come up short so I'm wondering if someone could share some advice.
The attached picture has my current setup with my existing QHY8-Pro - the field flattener is M48 on the telescope side and M42 on the camera side. I've been having issues with both image tilt and severe vignetting which I want to eliminate. To address the tilt I've ordered an adapter for the focuser which will mean I can thread my camera on instead of clamping. But for the vignetting, I'm wondering if the M42 tube is too small for the sensor?
The QHY16200a is an even bigger chip than the QHY8-Pro and hence I'm wondering if I should be investing in a field flattener that is M48 both ends? Would an M42 thread be big enough to illuminate an APS-H sized chip?
If so, can anyone recommend a field flattener that would be appropriate? Any suggestions would be much appreciated, cheers!
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KAF16200 sensor has a 34.6mm diagonal. The QHY8-Pro has a 28mm diagonal. So the KAF16200 is a fair bit larger.
Generally speaking the larger the aperture of the tube and adapters the better. Vignetting is the consequence.
Vignetting though often is corrected easily with flats so I would not get too concerned there. Round stars to the corners is what you need to concentrate on. That comes from a flattener with a corrected circle in this case at least 34.6mm in diameter.
A full frame sensor has a 44mm diagonal. 2 inch filters are plenty to cover the APSh as they will also cover a full frame easily (2 inches is 50.8mm).
Threaded adapters can still have tilt as the tilt may be in the focuser, slightly off adapter threads, not correctly seated dovetail adapters etc.
You may need to pack out the camera if the tilt persists once you use the threaded adapters. Its easy enough. I can give you a write up of how to do that and I have posted a writeup recently about it.
You should be fine.
The 16200 sensor is one of the nicest CCD sensors only bettered by the 16803.
Greg.