I've noticed that the result returned by the astrometry.net solver returns a "size" value that is exactly double the results returned by KStars FOV calculator. I've looked at other tools and they would appear to confirm astrometry.net's solution FOV.

Am I misinterpreting the astrometry.net solution, or is there some other discrepancy here? I've checked and re-checked that I'm properly entering objective diameter, focal length, etc.

From the picture, the values returned by Astrometry.net appear to be correct. For a 400mm focal-length f/2 200m Canon lens, attached to a ZWO ASI294MC (4144 x 2822 w/4.63um pixels)
http://nova.astrometry.net/user_images/ ... #annotated