Re[2]: [Leica] Re: Tri lens "Retrogressive?"/ Erwin / Marvin

[Peterson_Art@hq.navsea.navy.mil]

     Thanks, F. J., but as a computationally challenged English major, I 
     could not tell an inch from a millimeter if my life depended on it.  
     And besides, we here, on whatever side of the ocean this is if yours 
     is "the other side," tend to just round off all our millimeters to the 
     nearest inch anyway.
     
     Art Peterson
     
______________________________ Reply Separator _________________________________
Subject: Re: [Leica] Re: Tri lens "Retrogressive?"/ Erwin / Marvin
Author:  leica-users@mejac.palo-alto.ca.us at internet
Date:    2/13/98 10:39 AM

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
>