I do most of my astro-imaging with a monochrome CCD camera that lets me use a variety of filters.  This provides the best image quality and flexibility, but there are 2 significant drawbacks:  First, because of the expense of these specialty cameras, I can only afford one with a fairly small sensor (the same size as digital cameras using the “four thirds” format, which is smaller than the typical APS-sized DSLR).  Second, capturing a color image takes much longer because you have to take separate red, green, and blue exposures (and sometimes luminance exposures as well).  Processing these separate exposures can also take more time, but that doesn’t concern me much – it’s just the valuable imaging time that I want to make best use of.

DSLR cameras are consumer products, so the cost is much lower than an astronomy CCD camera, and you can get them in much larger sensor sizes.  I chose the Canon 6D, which is a full-frame camera, meaning it’s sensor is about the same size as 35mm film frame, or 4 times the size of my CCD camera (and at a much lower cost).

Here is the camera mated with the William Optics Star71 scope:

This scope has a focal length of 350mm (f/4.9) and with the 6D provides a field of view of about 6 by 4 degrees, enough to easily shoot the Orion, Horsehead, and Flame nebulae in a single shot.  To do this with my CCD camera I had to use a 200mm camera lens, which produces significant optical aberrations.

Here’s a test shot taken (in daylight) with this scope and camera:

Hopefully, the sky will be at least partially clear tonight so I can do a star test with this setup.

Of course, one can also mount a camera lens on the 6D for even wider shots.  I use a Nikon camera for my “terrestrial” photography and have only 1 Canon lens that will fit the 6D (and it’s a pretty poor lens).  Curiously, Canon full-frame cameras do not allow you to mount their lenses that are designed for smaller sensors (the EF-S type), but any Nikon lens can be mounted on the Canon body with a simple adapter.  I’ve already tried it with the Sigma 18-35mm f/1.8 zoom lens, which is designed for the smaller APS-size sensor (what Nikon calls the “DX” format).  As expected, the corners of the frame are not illuminated at all when the lens is set to 18mm, although it does cover the full frame at 35mm.  Even so, this lens/camera combination might be useful for meteor showers and such – you just have to crop off the outer edges.  It would still cover a somewhat larger area than the same lens would on a Nikon DX body.

I hope to report soon on the image quality tests, but am confident that the 6D will yield very good results with regard to noise level and sharpness.