Quote:
Originally Posted by kinetic
Hi,
I have read a recent post about the GSO RC-8" scopes
and field flatteners and people using CCDInspector to
check the flatness/ collimation of the OTA /CCD image train.
Could someone possibly please tell me if these two images
which are, pretty much, optimum resolution due to very good seeing
show any sign of field curvature or collimation defects? EDIT: see below
Thanks in advance.
Edit: sorry , didn't realise there was a free trial...
Here is a screengrab....there are differences in the two images.
Does this mean collimation is out? Or is this a field flatness issue? 
I'm not sure why there would be differences either?
Steve |
Hi Steve, as Bert suggested you need to take the shortest exposure you can of a uniform star field devoid of any nebulosity. If there are any bright star around try to keep it in the center of your field. Otherwise the information you'll get from CCDIS will be affected. Why short exposures? Because field rotation or any other tracking issues will be translated into different aspect%, FWHM and it's going to pollute your data. Then you can start tweaking things. The advantage of centering a bright star too is that the halos/reflection will give away any misalignment.
