Quote:
Originally Posted by gregbradley
I also used CCD Inspector which would help show which way it was out as well.
CCD Inspector is good but if I got a good result from manually correcting tilt I would find it was senior to what CCD Inspector would say as occasionally it would not give the same answer twice on the same image. But if you know how your camera is oriented with regards to the images then it does give an idea as to which way the camera needs to be packed out. Its another tool. It can also be helpful to use it to know when to stop!
Greg.
|
After our conversation last week I went back and worked out where things where things needed packing out. I am not really a fan of CCD Inspector but use it more out of curiosity really. I need to install my Atlas to get a workable solution here and that means taking a few measurements on my next visit to the observatory. Using the Atlas will solve the sag problem which I believe is causing 90 per cent of the problem with the stars. I never had this problem with the FSQ or the TSA holding up the QSI. So I doubt that the QSI is not square to the optical axis which means it is the focuser not being able to hold up the camera. It might only be a few microns but its enough to cause imperfection.
Quote:
Originally Posted by Slawomir
Greg,
Through my investigations I've found that CCD Inspector can be very helpful, but one needs to take at least 10 dithered subs (20 is better), and calibrate them before making measurements. Stars need to be sufficiently exposed too (not too short, not too long). Then results given by CCD Inspector are very precise each time. It allowed me to fine-tune tilt in my imaging train and now PI reports eccentricity in my subs just under 0.29, which equates to 96% round stars across the entire frame.
Paul - the stars are really good now, but I feel that like me, you won't stop until you will get star shapes at least 95% perfect  |
Yes Suavi, you know me rather well. I hate losing even a few pixels off the images so I will work a bit more to solve the actual problems. This should provide a clear path for others to follow.