Considering Full Width at Half Maximum (FWHM)
Think you know what your image FWHM is? Guess again! I look at factors affecting FWHM and compare values calculated by NINA, ASTAP, PixInsight, and ZWO's FITSView. Pick your favorite number! We also take a look at the effect of Air Mass, Eccentricity, and BlurXterminator.
Some reference videos:
Airy Disk, FWHM, HFD, and HFR:
• Telescope Resolution, FWHM, and HFR
Using "Maximum" FWHM for Image Grading:
• Maximum FWHM Grading Criterion