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: "Greg J. Lorenzo" <gregj.lorenzo@shaw.ca>
Date: Thu, 31 Jan 2002 20:19:50 -0700
References: <3C587731.9070406@shaw.ca> <p05100312b87f55f3738a@[192.168.1.33]>

Hi Christer,

I plan to test at all apertures with the Leica B&W test negatives, but 
concentrate on f5.6 through f11 with print comparisons of a range of 
negatives from extra thin to thick and in-between.

I had not thought of moving the negatives position off centre to test 
the corners and your suggestion here is a good one that I will also 
include in my test process.

I only had a couple of hours last night to get everything set-up, but I 
hope to spend several hours Sunday afternon printing, comparing and 
printing some more.

One real apparent difference last night is the Schneider lens is 
noticeably faster than my 5 year old Focotar.

Regards,

Greg

Christer Almqvist wrote:

>> 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



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Replies: Reply from Christer Almqvist <chris@almqvist.net> (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)
Message from Christer Almqvist <chris@almqvist.net> (Re: [Leica] Schneider 40mm f2.8 APO-Componon Lens Enlarger Lens)