[Leica] Camera vs. Enlarging lenses

["Kotsinadelis, Peter (Peter)" <peterk@lucent.com>]

Jim,

In a sense you're right but I don't think 3-D is the term to use.  Let me
explain, camera lenses are used for distances from about 3 feet to infinity.
Enlargements go from 1:1 to around 10:1 whicih implies a long-conjugate
distance that varies inches instead of feet. The range of object distances
for the enlarger is within the closer focusing distances of the camera lens.
High aperture lenses, such as camera lenses, suffer from field curvature and
other problems and this shows up at hihgher magnification.  This is the
reason not to use a camera lens as an enlarging lens. Enlarging lenses are
generally more symmetrical in their design, are not designed for high-speed
(fast apertures), and provide for greater flatness of field.  The lateral
color of the enlarging lens is typically much better corrected, and the
longitudinal color also needs to be corrected so that best focus agrees with
the best focus for enlarging paper.

Peter K

- -----Original Message-----
From: Jim Brick [mailto:jimbrick@photoaccess.com]
Sent: Thursday, February 04, 1999 5:51 PM
To: leica-users@mejac.palo-alto.ca.us
Subject: [Leica] Re: Leica Enlarger Lenses


Camera lenses are designed to capture the 3-D world. Enlarger lenses are
designed to project a flat image on a flat baseboard. You can, of course,
use a camera lens on an enlarger, but compared with flat field enlarger
lenses, it's a waste of time, money, and effort. It's like saying "I have a
tractor", " "why do I need a car?" A tractor and a car have wheels, engine,
and a seat or two. You should not take a long trip, or a date to the movie,
on a tractor. You should not plow a field using a car.

You will get inferior results with a camera lens on an enlarger.

Jim

At 08:19 PM 2/4/99 -0500, you wrote:
>I've been reading the messages on Leica enlarging lenses. Couldn't you just
>put say your Summarit 50mm f/2 screwmount lens on the enlarger or even
>the elmar? What would be the downside. Forgive me if this is a stupid
>question.