No, my bad, you did say half the size, I'm the one that got it mixed up with brightness. And I don't think Dave was too offended; he did add a smiley in there to let you know that. :-) Dave does have a great performer of a scope from what I remember at Wolf Creek by the way... Rich --- Chuck Hards <chuckhards@yahoo.com> wrote:
Rich, you are not a pest, and I'd be disappointed in you if you stopped asking these questions!
But you are correct, a fast scope is no real advantage if you are shooting eyepiece-projection, other than placing lower physical demands on your mount.
(Correction: I should have said 1/2 the size at the image plane, for half the focal length, or 4X the brightness...I'm just so upset that I ticked-off Dave, that I can't think straight!)
C.
--- Richard Tenney <retenney@yahoo.com> wrote:
My question obviously does belie my complete ignorance of astrophotography and the various methods used to image deep sky objects. When I read that a short focal length scope can photograph a given object X in "half" the time as a longer focal length scope of the same aperture, I see now what they didn't tell me is that the resulting image on the film is also 1/4 the size -- that's a big "duh". So I still fail to see the photographic advantage of a fast scope, unless what is imaged is huge (e.g., the veil nebula) and image size isn't all that important, right? Am I thinking straight here? At any rate, I'll quit pestering the list with my ignorance and go check out a few books on astrophotography and get a clue how this all works.
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