[Leica] Re: up one format on enlarging lenses. NOT!

[Jim Brick <jimbrick@photoaccess.com>]

I would never call Mark's LUG dialog ranting. Far from it. It is simply a
satirical way of expressing a thought. Usually a true and correct thought.

The ONLY reason to go up in enlarging lens focal length is if your enlarger
light mixing chamber is insufficient. You should be able to use a 40mm lens
on a 35mm enlarger w/o fall-off. If you cannot, you have a lousy enlarger.
If you cannot use an 80mm lens on a 6x6 enlarger, same problem. The
enlarger. Likewise with a 150mm lens on a 4x5 enlarger.

Emulsion has a thickness. To produce the ultimate print, your enlarger lens
should be "similar" to the taking lens. When the emulsion is exposed
through a wide angle lens, the light rays (especially in a camera without a
mirror) at the edges of the film hit at an extreme angle. This is why a WA
frame is larger than a normal or telephoto frame. The emulsion is exposed
at a "depth" running at an angle (not perpendicular) from the surface of
the film (with WA lenses.) If you use a 90mm or 135mm enlarger lens to
enlarge a 35mm negative photographed with a 21, 24, 35mm... lens, the
enlarger lens is looking at the side of the image recorded at the edges of
the film. Use a WA enlarger lens (40mm) and the angle of view more
approximates the actual taking angle of view. Edge sharpness is increased.
This, obviously, only effects very large enlargements (which is usually the
case with 35mm negatives), but the phenomenon is indeed there. Enlarge a
4x5 or 8x10 neg to 20x24... no big deal. Enlarge a 35mm neg to 20x24... you
need to pay attention to every detail.

It's the light mixing chamber that needs to be a size or two larger than
the negative format for proper enlarging. Not the lens.

Jim : "Not" one of the picket fence "cult" and proud of it!


>Mike Rabiner wrote:  "Fred Picker taught his popular cult the necessary
>advantages of going up one
>format on enlarging lenses but I never got his book or bought his print of
>the
>white picket fence."

At 09:57 AM 2/28/00 -0600, Alec Jones wrote:
>
>I'm not sure you ever read his books or newsletters either, Mark.  Had you
>done so, you would know he suggested longer lenses would produce a more even
>image.  He had it on good authority.  Saint Ansel, Book 3, Page 29 [later
>series] said:  "The lens must also "cover" the negative area with minimal
>fall-off at the corners. Using a lens of longer focal length than"normal"
>will help avoid this fall-off of illumination; it will also help ensure good
>definition at any aperture, since only the central portion of the lens's
>field of view, where resolution is highest, will be used. ..."
>
>Sorry, Mark, but he makes lots more sense than your ranting!
>
>Alec Jones : One of the "cult" and proud of it!