Archived posting to the Leica Users Group, 2002/01/31

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Subject: Re: [Leica] Schneider 40mm f2.8 APO-Componon Lens Enlarger Lens
From: Christer Almqvist <chris@almqvist.net>
Date: Thu, 31 Jan 2002 21:36:32 +0100
References: <3C587731.9070406@shaw.ca>

>A blue box arrived at the house today for my V35 enlarger with 
>Schneider's 40mm f2.8 APO lens inside.
>
>I believe Erwin in a LUG posting some time back called this lens 
>superior to Leica's 40mm F2.8 Focotar lens. No mean feat.
>
>Now I'm planing to find out for myself and post the results. I plan 
>to do a series of side by side tests using the same negatives, paper 
>and chemistry. The enlarger and selected lens apertures will also be 
>the same for both lenses and each test series will be fully 
>completed before I turn the enlarger off for the night.
>
>Suggestions on testing processes from Luggers who have done this 
>type of testing before would be appreciated.

Greg:

just a few thoughts:

I am sure the Schneider APO is better fully open than the Focotar 
fully open, but this is not relevant. I think you should do the test 
at your normal working aperture. Say this _has been_ 5.6 and then it 
would only be relevant what the difference is at that aperture, 
UNLESS you  always wanted to work at 4.0 but found this was not 
practicable because your prints did not turn out sharp enough at that 
aperture.

I do not think you will see much difference unless you enlarge at 
least 12X, better yet 16X. This does not mean that you have to use 
very large paper  ;-)  Just enlarge part of the negative.

There will probably not be much difference between the two lenses if 
you look at centre of the picture. You may find it more interesting 
to check the difference in the corners. I suggest you move your 
negative so that the centre of the negative is projected in one of 
the corners, as the negative itself may be less sharp in the corners 
and that may make it difficult to judge the difference between the 
enlarger lenses. Or do you have a special test negative?

What I think is a very interesting question is whether the APO will 
focus automatically. I know both lenses are 40mm lenses, but that is 
just part of the name, or a general classification, and one could 
well be 39 mm and one 41 mm focal length and that may affect the 
automatic focusing.

Now resolution (or sharpness) is one thing, and micro contrast is 
another. In my opinion the latter is important too, and it can be 
tested by enlarging a section of a negativ with average density, say 
caucasian skin in the shade, or some sort of fabric without much 
pattern. Here we come into the areas of taste, but it is important.

I am very curious to hear what your results will be.

Chrtis
- -- 
Christer Almqvist
D 20255 Hamburg and / or
F 50590 Regnéville sur Mer
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Replies: Reply from "Greg J. Lorenzo" <gregj.lorenzo@shaw.ca> (Re: [Leica] Schneider 40mm f2.8 APO-Componon Lens Enlarger Lens)
In reply to: Message from "Greg J. Lorenzo" <gregj.lorenzo@shaw.ca> ([Leica] Schneider 40mm f2.8 APO-Componon Lens Enlarger Lens)