Quote:
Originally Posted by blink138
do dark frames need to be done at the prime focus if lights have been done that way and flats?
i know temperature is important but is focus?
pat
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Darks can be shot with the camera even off the scope, so are bias frames. All you need is to make sure it's dark and there is no stray light. Most cameras these days have a regulated TEC so you don't have to shoot on site at the time you do your light subs. I have a library of 40x20min darks to make a master dark because I never shoot subs longer than 20min and you can scale the darks down to calibrate shorter light subs. It's a good idea to reshoot your darks every 6 months or so.
For light flats, I use an EL panel and I shoot them in the dark so there is no daylight. You need to be in focus accurately to shoot flats. I usually shoot 80 of them to make a master. Subs duration varies from 1s up to 8s for NB or even 20s for IR at long FL. All depends on the scope and filter. I also shoot dark flats of the same duration at the same temperature to make a master bias that I subtract to the flats so they don't over correct. I always shoot flats and bias after every imaging session. Unless the camera hasn't moved or rotated if I image for a few nights.