21 Feb
2003
21 Feb
'03
2:02 p.m.
--- Richard Tenney <retenney@yahoo.com> wrote:
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?
Yes. A telescope with a camera attached IS a camera lens. Aperture alone determines flux density (througput). Focal length determines magnification- and now you just invoke the inverse-square law for brightness. Twice the focal length, twice the mag., 1/4 the brightness. C. __________________________________________________ Do you Yahoo!? Yahoo! Tax Center - forms, calculators, tips, more http://taxes.yahoo.com/