Quote:
Originally Posted by troypiggo
I don't know of many people that use overscan other than Rick. I don't know if or how he does flat calibration, but if he does, then he clearly isn't having this same issue or he'd have mentioned it.
|
Yep, I use overscan and do traditional bias/dark/flat calibration. I dump everything into BPP and it just works.
Quote:
Originally Posted by multiweb
You'd think so. I checked my flats this way when I collect them. Make a master of let's say 10 subs then 20, etc... then flat field a sub to check. They always flat field correctly. If I have the wrong bias which I like to call "dark flat" as opposed to "light flat" then the scaling is all over the place. I never successfully managed to pixel math them to get a proper flat fielding either. As everybody else probably did I've also done a lot of reading in the past trying to figure it out. I know the "maths" say 1/3 or full well, blahblahblah. In practice it never worked for me. It was trial and error until I got the levels I wanted. I don't try to understand why anymore. I just use the exposure times and ADU that work for my camera and scopes. I've found it to be scope dependant and also filter dependant unfortunately. I always flatfield and fully calibrate all my light subs. Always.
|
Flat framing does seem to be a black art. I have been fortunate and it has always just worked for me. If it hadn't I guess I might have developed some better diagnostic tools and would have more useful suggestions for Chris
That said, apparently we've got some problem with dawn and dusk flats behaving differently at SRO. I haven't had a chance to dig into that yet but maybe my first flat framing nightmare is about to start
Cheers,
Rick.