Quote:
Originally Posted by gregbradley
Use flat darks and no bias with these cameras. Perhaps that will help.
I have the QHY294m and used it to an extent. I don't recall issues with flats. Flats can look odd with this sensor, but from what I have read it calibrates fine.
One area your image could be better, the outer rings are usually shown as being blue. Quite blue in some images. You could up the blues.
Greg.
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Thanks Greg. Will look at the blues.
Yep - I don't use biases and do use flat darks. Did same with the 1600MM.
Re flats, yeah the Ha and SII are really odd, but calibrate out. What I have an issue with is the brightness of the corners of the lum dropping off a bit too much and not calibrating properly - I end up with a bright band near a couple of corners. I have 31mm filters and have them a tad further from the camera than normal as I have the filter wheel backwards!!
With the wheel in the correct way round and the Ha filters one (the correct) way, the Ha flats were very very odd - i.e. serious reflections that were way beyond calibration. But I might try it back with the wheel the right way round but with the narrowband filters the other (wrong!) way (i.e. reflective surface to the camera). I'll see if the lum is closer to working like that.
Oh - and an extra thing to address at the same time is my reducer flattened enough for the 1600 in the corners. It is not doing it for the 294 as I think those corners are a little bit further out (only about 4 or 5% but enough to cause an issue). So I need to move the reducer (closer??) at the same time to see if it helps. It'll give me a smaller image scale too - which I'd prefer, as I like about 0.7" per pixel. But with the OAG to contend with too, I might be lucky to find a solution where everything fits!!!
Some experimentation to do
That is seriously good. 
I imaged NGC 6188 during the first half of the night and switched to this after midnight - and let it run through to 5am on those nights without cloud.
