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| p.7 #9 · Nightscapes using AstroTrac Tracking Mount |
Did you process the data in Photoshop (or similar)? Or, is that the image directly from stacking?
Use an iterative stretch in Photoshop using the Levels tool (being careful not to clip the left/dark side of the histogram). I try to make sure that none of the 'black'/space areas in my images are truly black...rather an RGB values of around 15-30 or so. Also, set a gray point somewhere in a darker portion of your image to align the RGB channels and you'll get a more natural color for the stars and nebulosity.
If you are shooting from a light-polluted area, eventually you will reach a point where you're bringing out the sky-glow rather than the nebulosity...but I'll bet that you've got more in there than what your current image shows.
There's not much extended spectrum (Hydrogen) in the Pleiades (unlike M42), so your current gear should do quite well on this target without modifications.
I tend to stack sub-exposures all the same length...I'm not sure there is value in mixing different exposure lengths in the same stack. If there is an area that you don't want blown-out, you can stack shorter subs in a separate image and overlay with layers.
Its not an Astrotrac image, but I shot this M45 with a cooled-CCD on an equatorial mount (with a very dark sky), using 10 minute subs with a total of around 5 hours exposure combined.
Love your image! I wish I could leave my shutter open for 10 minutes.
The DSS calibrated stacked image is very bright because of LP. In Photoshop, I start with a initial black and white point Levels without removing any image data for each individual channel. Then I move the midtone slider to the left to see if there is any nebulosity data. There is almost none...
I think the main problem I'm having is light pollution and exposure times. I found something about it related to this image:
I pushed my image a little further. It's starting to loose IQ at this point...