Quote:
Originally Posted by sunslayr
Thanks for your advice, honestly it was probably a mix of all of the above. I might give the trial of ccd inspector a go and see if I can improve my focus and collimation. I think at the time I was getting an average of 4" for my FWHM. What I'm not sure of is how to get the distance for my coma corrector right. There seems to be conflicting measurements of the qhy8 ccd distance. Is the only way to check the distance is by adding a spacer, refocusing and then checking the FWHM of all the stars and then repeating?
|
Hi David,
4 arc seconds is never going to give you a sharp image.
I got my spacing correct using a Varilock device as per here:
https://www.flickr.com/photos/247194...in/photostream
As you said - I used a trial version of CCD inspector here:
http://www.ccdware.com/products/ccdinspector/
There is also a great trick to get the collimation right
that only requires a laser collimator & a Barlow lens.
You need a paper re-enforcement on the mirror coloured black.
You basically look for the shadow of the re-enforcement in the 45 degree
viewing face of the laser collimator.
You adjust the 3 screws on the mirror until it's central.
I found focusing was very difficult without an electric focuser.
That way you're not bumping the scope while trying to focus.
I have a motorised 2" TS 2" UNC V-Power Newton Crayford Focuser.
The QHY software has a focusing software feature
which helps.
Still - your first image is excellent compared to whatever I did.
You're almost there with a few adjustments.
cheers
Allan