Hi,
> > Just been looking at pages listing all the
> lenses I'd like, and I noticed
> > that the brightness seems to peak at 50mm.
>
> Even Leica tops out at f1 with its 50mm
> Noctolux for the M series
> rangefinders. (Understand a f1 would be just
> about impossible to focus with
> an SLR.) I seem to remember hearing that
> Vivitar had some kind of super-fast
> Vivitar One series lens which was supposed to
> be f0.95 or some unbeliveable
> speed.
There's quite a number of medical lenses that go
below f1.0. I've read an article in an astronomy
magazine about an, I believe, 75/f0.75. Milky
way handheld !
If I understand it correctly, the f is the focal
length divided by the diameter of the front lens
(i.e. where the light gets through) in case you
don't lose any light internally. So the formula
works perfectly for mirrors, but not for lenses.
Hence the wide angles with huge lenses :-)
Anyway, a 300mm/f1.2 would have a diameter of
25cm of glass at the front. That by itself would
already weigh more than the current 250/2 :-)
Still wondering about how to construct that
8-800/f1.0. It's not enough to have a glass disk
of 80 centimeters, it's got to be very round,
because of the wide angle effect. You may laugh
! But once upon a time, it was unthinkable that
we would ever see a 28-300, and that's a common
lens now. It's not f1.0 though :-)
Peter.
=====
--
Peter Leyssens --- leyssens@xxxxxxxxx
-- http://www.geocities.com/leyssens --
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