Quote:
Originally Posted by Paul Haese
Yep having a PME means you can accurately do a meridian flip and only lose a couple of pixels at the edges of the image.
That said, this is quite a nice version of the trifid. Good colours and quite smooth processing.
Just one question though. Why do you have round stars in the top left of the image and all the way around in the other corners the stars have some elongation? Are you using a reducer or flattner? Does the QHY9 have a tilt problem? I see this a lot with images taken with these cameras and wonder is the sensors are not square to the line. It is a minor thing but still getting round stars is the goal of most astorphotographers I would think. Your thoughts Doug?
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Thanks Paul, an interesting question indeed. One that I haven't really spent a lot of time investigating as yet. I haven't had enough sky to waist tracking it down at the moment but I will say I am inclined to think it is a bit of sag somewhere in the imaging train or focuser somewhere.
I have run a dial guage accross the CCD itself and it seems very close to perfect.
I have added a couple of CCDInspector curvature maps frtom this image and the M17 image which does seem to indicate some inconsistancy in the imaging train somewhere.
Both these images were taken within a couple of days of each other without making any adjustments to the camera or imaging train but just taken at different levels of the sky and different times.
This is something for me to chase up when time allows but with a holiday coming and little chance of clear skies between now and going away I just can't see very much happening soon.
The first image is this image and the second is of M17.