Do the flat frames for bad pixel maps need optics?

Hi Blair

Your darks must be the same iso, time(seconds - minutes), temperature, as the lights.  At least you can do these while packing up your gear for the night.

Flats are to see dust bunnies, vignetting and other imperfections in the complete optical train.  Must be done at same focus as lights right after imaging and before darks especialy on a DSLR as you might move the focus accidentaly when you cover the lens for the darks. 

https://www.astropixelprocessor.com/how-to-create-a-bad-pixel-map-bpm-by-sara-wager/

Regards

teve

@solo05 Thanks for the response. Yes for calibrating my lights I'm aware the darks need to have the same settings and for flats to calibrate lights they of course need to be with the same optics, focus, etc.

I'm specifically interested for only generating a Bad Pixel Map, not in calibrating Lights. If you're only trying to find the bad pixels why would the optics matter?

It wouldn’t indeed. Unless you have cold pixels, those show up in flats, but modern sensors don’t seem to have those a lot anymore. So purely for the BPM you can use a long dark (longer is noisier and better for that).