Quote:
Originally Posted by Shiraz
thanks for the feedback and info.
Reworked the theory and will attempt to validate it tonight if all goes well - will start a new thread, since it could possibly be useful to others who might not read this one.
Looks like you can control flat-induced noise simply by making sure that you have at least 10x as many total flat electrons as you have total sky electrons. eg, if you take 100 lights where the sky background in each is 3,000ADU above the bias, you need to take 100 flats if you use 30,000 ADU flats. It has nothing to do with how many subs - just how many electrons - so if you took flats with say 10,000 ADU in the above example, you would need to take 300 of them. If you image for a long time, take a lot of flats, if you have bright sky, take a lot of flats.
Not yet sure how much of an issue colour is for noise reduction - guess that dust on filters might make separate flats worthwhile for getting rid of bunnies if that is a problem. Quite a bit of other interesting stuff to look at as well, including the possibility that past images can be improved by using two different sets of flats - one to control noise and the other to get rid of vignetting etc  .
Regards ray |
Holy hell. My subs are around 3300ADU so I need 33000 ADU flats. So if I take flats at 30000 ADU I will need 10 flats; is that right? What about if I take the at 26000? Am I to assume it would 13? Confused now.
