Message posted by paulw on November 09, 2009 at 10:47:29 PST:
I admire your interest in wanting to do some A51 photography but I wouldn't be caught dead taking a 12 or 16 inch Dob up that peak. For one, the weight and especially bulk would make it near prohibitive. Second, It won't give you much in terms of detail. Dobsonians are light bucket telescopes. Their large diameter mirrors allow for greater light gathering power but Dobs tend to have low magnification in terms of focal length. Typical Dobs in the 12-16 inch category will have focal length ranges between about 1200mm and 1800mm. For point of comparison my 5 inch Celestron Maksutov does 2000mm. If you were to hook a 35mm camera or a CCD to an 1800mm focal length 12 inch Dob you would get less magnification than by hooking up that same camera to a 2000mm length telescope of smaller diameter. Light gathering ability is nice to have when you want to look at dim night sky objects but it doesn't help much if your subject is terrestrial and is being viewed during the daytime. Yes, your shutter speeds will be faster but will that buy you more detail? Probably not. Also keep in mind that the atmosphere itself provides a limitation factor. Even on the clearest of days a law of diminishing returns will kick in. For example, a 3000mm telescope might not produce a more detailed image than an 1800mm telescope simply because of the limitation provided by atmosphere clutter. A 3000mm telescope will provide a larger digital image than a 2000mm but not necessarily a more detailed one. To be honest, telescopes with their light gathering abilities and focal lengths are only part of the equation. It is just as important, if not more so, that you be at the top of that peak when the atmospheric conditions are optimal for viewing. It is also very important that you have a handle on digital post-processing technique. Learn image stacking.
In Reply to: Telescopes at tikaboo peak questions. posted by Watcher on November 01, 2009 at 16:36:25 PST:
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