Quote:
Originally Posted by Tilt
Hmm, I'm kind of new to imaging. How do you keep from over exposing the core of the Lagoon Neb? I am imaging right now and the shots coming in look to be a little bright in the center. I am using the 350D on the 70-200 set at f/2.8, ISO1600, 120sec exposures. Should I knock back the ISO? Or set the aperture to f4? I'm dont have any guiding, but it seems to be tracking well on the EQ6.
Michael.
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Hi Michael,
That image was done at f4, perhaps that stopped core burn-out to a degree, but I did a little PS magic in curves (just a little) to pull back the core brightness on that pic. Certainly stopping down the lens will sharpen up the stars and nebular detail (but I do autoguide so I can push my exposure times to compensate for this, although for me f4 is the fastest I've got!!!)
As to iso setting - not sure, experiment.
I've found since getting the 40D modded I use iso1600 all the time - I think it's a "maximum from the camera" type of attitude - I try to suck the marrow from the bones of my imaging sessions (YUK!!!!)
You could also try shorter exposures at f2.8 to reduce core burn then combine the shorter and longer exposures with a layer mask technique to save the core but bring out the faint nebulosity too as per this tutorial...
http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM
Cheers
Doug
