Hi Greg.
I am planning a new system to image galaxies and wanted to understand the issues re sampling, so your confirmation of results to date is helpful. I was most concerned about maximising resolution and that means selecting an optimum pixel size for the scope/camera combination as the first step after choosing the scope.
the spreadsheet is nothing particularly special, but it does include the main variables and gives some idea of what is important. I wanted to look at system issues and used the Nyquist sampling requirement for a Gaussian - 2.35 pixel per FWHM - but of course, seeing cannot be predicted at anything like that precision, so 2 or 3 are probably just as useful. Conclusion to date is that, for seeing limited operation, I need at least 10 inches of aperture and a precision tracking mount - the spreadsheet is being used to evaluate various possible scope/camera combinations that fit those initial guides. However, I posted some results for other fairly widely used combinations of scopes and sensors for interest.
the 2 arcsec per pixel rule of thumb is pervasive on the web - a very quick search resulted in
http://starizona.com/acb/ccd/advimagingdetail.aspx
http://www.skyandtelescope.com/howto...y/3304356.html
My point was that it is too coarse and we agree on that.
Added the CDK17 to the spreadsheet - the 16803 is a much better choice than the 8300. With that focal length and aperture, you will always be seeing-limited and the 8300 would be down by a factor of about 2.5x in sensitivity compared with the 16803 - for no additional resolution, bloated looking stars and a much smaller fofv. The 8300 should definitely only be used with smaller scopes.
You raised a number of other system issues that should also be considered. Couldn't agree more. My current planning process is an attempt to find a cost/capability sweet spot that will provide seeing limited resolution with manageable imaging times and acceptable image quality - quite a challenge and fun as well.
anyway, thanks for your comprehensive post.
regards Ray