From a blue zone on a night of high airglow, here is 9-minutes of integration time on the Horsehead nebula. 300 mm f/2.8 lens at f/2.8, Stock Canon 7F Mark II digital camera. ISO 1600 daylight white balance, 1-minute sub-exposures. No darks, no flats, no bias.
Tracking with an astrotrac. I have 70 minutes of exposure but decided to process just 9 minutes to show what can be done.
Processing: photoshop ACR raw conversion with lens profile, stack in deep Sky Stacker with no calibration, Stretched with rnc-color-stretch then final tweaks in photoshop. Just a few minutes of my time. Prepping the image for this upload and typing this description took more of my time.
More info:
http://www.clarkvision.com/articles/astrophotography.image.processing.basics/http://www.clarkvision.com/articles/astrophotography-rnc-color-stretch/This is a natural color image. The star colors can be checked against stellar photometry. The star color diversity is impressive in this region of the sky. Note the faint red stars, they have B-V > 2 (not the bright orange stars, which have B-V of 1 to about 2). The blue-white stars have B-V in the range of 0 to -0.5. The colors closely follow the color sequence in Table 1 at
http://www.clarkvision.com/articles/color-of-stars/ Solar-type stars have a B-V of 0.63 and appear close to white (daylight white balance).
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