Darks with different exposure length lights..

[andyhicks]

For example, if I'm imaging m31 or m42 where it's best to capture some shorter exposures for brighter areas and longer for the fainter detail, how would I go about taking darks?

Should I take a set of darks for each set of lights? How would I process this in DSS?

I normally take lights, darks, bias and flats and then give them to DSS to deal with, I always thought this was a bit too easy and after a bit of reading it seems I was right. Ive never calibrated my flats before, I assumed DSS did everything but I'm not so sure it does?

Probably a bit late for trying to get my head around this but the dark length question was bugging me!

Andy

[Starflyer]

As you say, you should take a set of darks for each different exposure length.

Last time I imaged M42 I took 3 sets of exposures; 8s, 60s and 300s, stacked each set as individual images and combined them by following this excellent tutorial. I was using the same camera, same mod as you and even at 8s the trapezium was a bit bright, the final image is here.

[ollypenrice]

I think Starflyer's image confirms the virtue of the method! It's a cracker. That's the way I do it as well, following Lodigruss.

Often you don't need shorter exposures (though for M42 you certainly do) because combining two different stretches of the same data will help with overly bright regions.

Olly