|
FWHM is commonly used as a measure of focusing and choosing stars for stacking.
Is the real point in that FWHM becomes unreliable once the central pixels come close to saturation?
Once you have a circle of saturated pixels FWHM has to be at least twice the diameter of the circle of saturated pixels.
So the moral of the story would appear to me - and to Craig Stark from the Nebulosity doco - do not use saturated stars to do any sort of measurement of focus, or alignment for stacking.
|