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Re: [OM] Lens Test update

Subject: Re: [OM] Lens Test update
From: Richard Schaetzl <Richard.Schaetzl@xxxxxxxxxxxxxxxxxxxx>
Date: Sat, 24 Jun 2000 19:30:44 +0200
Gary Reese wrote:

> Thanks for your observations and comments on curvature of field in the
> 35mm Shift lens. It is very good to know that it clears up at infinity.

> Well, I'm using a 60" wide map reproduced at 1:40 magnification...  

I real appreciate your work of testing Olympus lenses. Your testing
conditions are transparent and your different setups showed
interesting dependencies of different camera-lens combinations and
lens variants. Thanks to you, Olympus user are more able to choose the
right lens and setting for the job.
Your effort and that of many others on the list helped to improve the
situation of underrepresentation of Olympus OM stuff on the web and in
the public.
More important, your test helped to improve the Zuikoholic self-esteem
against the "big bad N*k*n, C*n*n syndicate" ;-)

Lenses designs are an compromise, optimized for different purposes
(and wallets). Lens test have to be standardized so the results can be
compared, so neccessarily the test has to be a compromise themself.
The reader has to consider this while judging a test. Problem arise
when the reader is to lazy to do such and just looks for the "best
lens". It's like looking for the "best vehicle", while an Porsche has
a better asceleration it's pretty useless if you need to transport
tons of sand. But exactly for the lazy readers is the single digit
ranking of Photodo.

> But a typical teen is not
> 2 dimensional, as any parent will tell you  :-)

Another point to consider, curvature of field might be desastrious in
an MFT test or for copy work, but is no problem with three dimensional
objects.

Another point were lens designer often had to compromise with is
contrast/resolution. I often wondered why older photographer judged
lense as B&W or colour lenses and I considered this as a kind of
superstition.
But I learned from an article in "Leica Photo International" it is not
an unbased rumor. In early designs, the designers had not the
technical posibilities as today (like aspherical and ED glass). So
they had to make bigger compromise, especialy at wide open aperture. 
The Mader design 50mm/2.0 Sumicron has superior resolution but not
very good contrast until stopped down.
The designer had known of this deficiency, but it was more easy to
improve resolution than contrast with the means of that time, while
the photographer had a better control over contrast using mostly B&W
film.
The new Sumicron has much improved contrast at wide open aperture and
(thanks to new technology) only sligthly lower resolution. So this
lens works better with colour film and one could call it a "colour
lens", while the old design was an "B&W lens".
The designer sacrifed some resolution for contrast because under
normal conditions super high resolution is not useable due to camera
shake.

> I
> longed for a macro in the shorter than 50mm focal length.  To the best
> of my knowledge only Novoflex marketed one (a 35mm probably made by
> Schneider), but it was only in the M42 thread.

Maybe an wideangle enlarging lens (35-40mm) might help?

> I can think of a copy application for a 35mm Shift: art work behind
> glass where you might otherwise end up with the camera reflection in the
> lens.

Exactly this sample was presented by Franz Pangerl in his "World of
the OM-System". He tried to reproduce an small daguerotype with the
help of an polarizer and the 35mm shift. I found the results
unsatisfactory because even in the small printsize of the book one
could clearly see that one side of the image was unsharp.
The 135mm MACRO lens and an shiftable bellows might have been a better
tool.

But again, for an tree dimensional object, like an blossom, this might
be no problem.

> BUT, the camera manufacturer might have adjusted for
> that with focus offset on the film plane. 

Minox has done this with their super micro cameras.


Regards

Richard



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