Any image captured by a camera set to RAW or RAW+jpeg.

"■ 12 bit. This is an optional bit depth for the Nikon D7000. Images are recorded at 12-bits per channel in the RAW file, and end up with 12 bits of information per channel that is translated during conversion for your image editor either into 12 bits within a 16-bits-per-channel space or interpreted down to 8 bits per channel.

■ 14 bit. At this default setting, the D7000 grabs 16,384 colors per channel instead of 4,096, ending up as 14 bits in a 16-channel space or reduced to 256 colors by the RAW conversion software that translates the image for your image editor. You’ll find that such 14-bit files end up almost one-third larger than 12-bit files, and that your camera’s continuous shooting rate may be reduced (which alone is a good argument for not using the 14-bit setting any time you may need to shoot bursts of images). 14-bit images are unmatched for HDR photography, however."

Hi Craig,
thank you!

The 50 light frames are 50 exposures of:
100mm f2.8, ISO 6400, 6 sec
THe 50 dark frames are 50 dark exposures (lens cap on, viewfinder covered) for the same exposure:
100mm f2.8, ISO 6400, 6 sec
The 20 Bias frames are 20 exposures (dark - lens cap on, viewfinder covered) of the least amount of light possible.
Smallest aperture and fastest shutter speed.

In actual practice I took about 55 light frames, but a few got culled because I had to try and track the movement of the subject.

All frames taken in the same conditions, temperature, humidity etc. For the 6 sec exposure I think I had the intervalometer set on 10 sec. I wanted to make I didn't fill the buffer, and that gave me a few sec to adjust the camera to track.
For the dark frames, I put the lens cap on, put the viewfinder cover on and then covered the camera/lens with a black cloth.
For the bias frames, same as above with adjusting the shutter speed and aperture.

When running the stacking software all the information from the different frames are aligned, which is why the stacked version is smaller than the original, my tracking could have been better :-)
then the different types of noise are reduced, as if by magic :-D

Thanks for the interest.
It is a lot of fun, and with a dark site, you should get amazing results. I am so close to LA and essentially right in town (small town, but town) I have a lot of light pollution.
So much so, that Andromeda isn't visible to the naked eye, and I still got this.
It was a practice run for heading to dark skies. I went the other day, but got caught up in my wide angle I never even put the other lens on.
Next time!

If I didn't answer your question, or you have others, feel free to PM me,
GT

Can anyone help me out. I just purchased the D7100 with a 18-140 lens along with a 55-300 lens. I thoroughly enjoy the camera and pic quality but I cannot understand the way the owners manual is laid out regarding all the camera functions. It is very confusing and is starting to force me to use Auto, Scenes and Effects more than I want. I even went back to the camera store where I purchased it and they would not give me the time of day and only referred me to a couple of Nikon publications
I would like to use ISO and aperture first and then progress but this may not be the best way
I don't know of anyone else with a 7100 other than each of you so any and all suggestions and recommendations are appreciated.
Feeling discouraged.