Archived posting to the Leica Users Group, 1998/02/13
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I think you are making a little mistake, mixing mm and inches (").
Focal length are expressed in mm. A 28mm f1.0 should have a diameter of
28mm and not 2.8" (71.12mm).
My 2 cents from the other side of the ocean
F.J.
- -----------------------
On Thu, 12 Feb 1998 Peterson_Art@hq.navsea.navy.mil wrote:
>
> Ok, Marvin, so how about a 28mm f/1.0 lens 2.8 inches in diameter, or
> a 35mm f/1.0 lens 3.5 inches in diameter!
>
> Art Peterson
>
>
> ______________________________ Reply Separator _________________________________
> Subject: [Leica] Re: Tri lens "Retrogressive?"/ Erwin / Marvin
> Author: leica-users@mejac.palo-alto.ca.us at internet
> Date: 2/11/98 4:51 PM
>
>
> In a message dated 98-02-11 15:07:50 EST, Erwin writes:
> <<
> I wonder why a 2.8/28 is considered a slow lens and a 2.8/280 is fast one.
> I would not regard the TriElmar as retrogressive just by taking a look at
> one parameter: the full aperture value. If that were the only criterium
> consider every medium format camera hopeless out of times and unworthy
> of any place in this high speed world.
> ========================================================
> >>
> Erwin - You know the answer to that as well as anyone ------------------
> In optical theory, a 2.8/28 lens has to be only 1" in diameter whereas
> a 2.8/280 has to be about 10" and therefore weigh a ton ------------------
>
> Can you imagine a 280mm Noctilux f:1 ???? 28 inches in diameter !!!!
> As for medium & large format photography, the larger formats are used
> for a different purpose than available light, which is the "forte" of Leica.
>
> Marvin
>