Re: [Leica] Summicron report part 1

[Erwin Puts <imxputs@knoware.nl>]

Outlines and fine detail is 5 and 10. Very fine = 20lp/mm, and extremely
fine details = 40lp. Exceedingly fine detail = 60 lines.

At last the results from a comparative evalution and test of the Summcron
50mm generations. On the bench we have a Summcron Collapsable with some
coating defects, a Summicron Collapsable in excellent as new condition , a
Summicron Rigid (7 elements), a Summcron DR (same generation) and the
newest Summicron-M (third generation).

General remarks.
There is a significant difference in optical performance between the C and
the R, NO difference at all between the R and the DR and  important
differences between the R/DR and the N.
The differences between the C with defects and the clean one are remarkably
small. A drop in contrast, a higher level of flare and a loss of micro
contrast when recording very fine details are visible. These differences
might or might not be important depending on user-expectations and shooting
circomstances.
All remarks below refer to the clean version.
The Summicron family from its first inception represents state of the art
performance. Results were examined under several viewpoints. The practical
testing  has been done at 1 meter and 5 meters and with 10 and 30 times
enlargements.
The pitfalls of testing and the responsability of the tester in presenting
the results have to be made quite clear at the beginning. As an example:
consider the rendition of the extremely fine details. Here the C is good at
1 meter and 10 times, but weak at 5 meters and 30 times. The N is suberb in
both tests at 30 times and here it is the emulsion that is the weakest
link. So if your normal shooting practice concentrates on handheld shots at
a distance from let us say 1 meter to 2,5 meters, you use 400 ISO B&W film
or the older generation transparancies from 200 ISO, and your enlargemet
requirements are modest, the C will suit you very well and the differences
with the other types are maybe not so significant. If you have the same set
of requirements and use the N, you are under-utilising its performance
potential. In fact you may use only 30% of its optical performance
capabilities. Of course you will see differences, but you might not b able
to recognize them.

Here are the condensed results (more in a few days on my site).
The Collapsable (#1377201) at full aperture shows a low contrast image with
soft outlines and the delineation of fine and very fine detail also quite
soft in the center. The outer zones show astigmatism, reducing the
rendition of very fine deatil, but fine detail is visible, but soft. The
corners are quite weak with only the fine detail and the outlines just
visible.
At 2,8 the contrast is a little better, but you really need f/4,0 to see
the extremely fine detail, but even now its edges are very soft. At f/5,6
the very fine deatil is now renderd with sharpish outlines. This
performance level has nw extended over the outer zones, only the corners
lagging quite severely.
At f/8,0 spherical aberration softens the center and from f/8.0 the general
performance drops a little. There is no curvature of field, hardly any
vignetting and no chromatic aberrations to speak of. Centering is OK.
At all apertures to f/4,0 there is a veiling glare softening the overall
image and suppression of bright spots is also weak.
The Rigid and DR are identical in performance (#1956284 and # 2116804).
At full aperture the overall contrast is medium but the rendition of very
fine details is a class better than the C. The outlines, fine detail and
very fine detail are clearly visible with good sharp oulines and a fine
micro contrast. Extremely fine detail is on the soft side. The outer zones
still show astigmatism and in the extreme corners only fine detail is
visible.
At f/2,8 the contrast is better and at f/4,0 the optimum is almost reached
with a center that has a sharp and contrasty rendition of extremely fine
detail. The outer zones are noticeably softer (and show traces of
astigmatism) and the corners are again lagging.
At f/5,6 spherical aberation softens the center, but the outer zones now
have a sharp representation of extremely fine detail.
From f/8,0 the quality drops slightly and more so at f/16.Flare is well
suppressed, as is chromatic aberration and curvature of field. Centering is
OK.
The Summicron-M new.
At full aperture a high contrast image is rendered with very crisp
rendition of extremely fine details from center to the very corners.
Astigmatism is gone except in the far zones. Exceedingly fine detail is now
visible with good micro contrast. At f/2,8 this lens has perfect qualities.
From f/8,0 spherical aberration very slightly softens the center and from
f/8.0 micro contrast drops a little. Flare is very well suppressed and all
other aberations can be neglected.
This lens at f/2,0 surpasses in all respects and criteria the DR and Rigid
at f/4.0 and f/5,6.
Especially important and very visible is the clarity of the image and the
extremely well preservation of exceedingly fine details. This lens can
render details in the order of a factor 2 smaller than its name bearer the
Summicron of the first generation. .
To save some email: no I am not testing the out of focus rendition.
Conclusions:
The C is adequate for out and about photographic activities and may have
very plesing subject rendition. The DR and the Rigid are much better, but
no match for the New. Optical progress here is quite visible, but special
precaution is necessary to exploit this level. The C and DR/Rigid are not
as good as the best of modern emulsions. The New however challenges the
capablities of the best emulsions and the expertise of the photographer.
Erwin