Re: [Leica] Retrofocus. was sharpness discussion

["Bryan Willman" <bryanwi@seanet.com>]

The real point here is that Retrofocus lens is
physically longer than its focal length.  So,
a 21mm for an M camera must be retrofocus,
since you can't fit the nodal point within 21mm
of the film plane.

A true telephoto (as opposed to mearly a long lens)
means one in which the lens is physically shorter
than it's focal length.  (Which also means it can
focus to infinity without having to draw the extension
of its focal length, which turns out to be a big deal
for view cameras, of all things.)

bmw

- -----Original Message-----
From: Raimo Korhonen <raimo.korhonen@pp2.inet.fi>
To: leica-users@mejac.palo-alto.ca.us <leica-users@mejac.palo-alto.ca.us>
Date: Monday, May 25, 1998 11:56 AM
Subject: Re: [Leica] Retrofocus. was sharpness discussion


Elementary - it=B4s an inverted telephoto design. Raimo ;-)

- ----------
> From: Mark <mark@steinberg.net>
> To: leica-users@mejac.palo-alto.ca.us
> Subject: [Leica] Retrofocus. was sharpness discussion
> Date: 25. toukokuuta 1998 18:02
>
> i have to ask, what is "Retrofocus" ?
>
> m