different exposure times

[brrttpaul]

Hi guys/ladies I am in the middle of taking some subs using maxim and I am doing some @60 secs some @180 secs and finnally some @300 secs.  I was wondering do I stack them as different groups I.e  all the 60 secs in one etc then stack the three stacked images or do i group them all together straight from the beginning , I have my flats,bias and also darks in the various exposure times just not sure on the stacking.

Cheers

Paul

[wimvb]

It depends on what you aim to do with them? The differenct exposure times can be calibrated with the same bias and flats, of course, but need their own darks.

Because you will have significantly more signal in the longer exposures, these would dominate if you stack them all together.

If you plan to combine them in a HDR process, you would need to stack them in groups, producing three masters (one for each exposure group).

There is seldom need to combine different exposure times. If you have enough of them, using only the 300 sec exposures would suffice.