Chuck, Can you explain the physics behind why short focal length scopes can achieve much faster photographic imaging times than longer f-ratios? Are we back to the camera anaolgy again here? (as you stop down the lens, depth of field increases, but so does the incoming amount of light vs. opening the stops up for more light, but the depth of field gets narrow). The missing piece for me still is, where is the stopping down occuring in two scopes with the same aperture but having different focal lengths? Sorry, I'm a bit dense with all this. Rich --- Chuck Hards <chuckhards@yahoo.com> wrote:
I did state that ergonomics was a consideration for going short.
A 30" f/7 Cassegrain would be much shorter than a similar-apertured f/7 Newtonian.
C.
--- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
Imagine a 30" f/7...
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