Archived posting to the Leica Users Group, 1998/10/10

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Subject: [Leica] Testing lenses
From: Nathan Wajsman <nathan.wajsman@euronet.be>
Date: Sat, 10 Oct 1998 23:00:09 +0200

My M6 has recently come back from a trip to Solms for rangefinder
adjustment. To make sure that the problem had indeed been solved, I ran
some tests last week. What I did was the following:

1) Mounted the camera on a sturdy tripod.
2) Focused on an object about 0.9 meters away until the image looked
sharp in the viewfinder.
3) With my 35mm Summicron (2nd version), I exposed at f2, f2.8, f4 and
f5.6.
4) Repeated the exposures without moving the camera but with the lens
focused at 0.8 m.
5) Repeated again, this time with lens focused at 1.0 m.

I then proceeded to do the same test with my 1.4/75mm Summilux
(apertures f1.4, f2, f2.8 and f4) and the 2.8/90mm Elmarit-M (f2.8, f4,
f5.6). Since the minimum focusing distance of the latter lens is 1m, I
had to move the camera back a bit, so that the subject to film plane
distance was about 1.1m.

I did the tests using Kodak's E200 film (I know I should have used Fuji
Velvia but did not have around the house). I looked at the slides on a
light table with a 10x loupe.

Some conclusions: first, it appears that my rangefinder now functions
correctly, as the image that looked right in the viewfinder was also the
best compared to the other two focus settings. Second, with the 35mm
Summicron there was a distinct difference in image quality going from f2
to f2.8. At f2 the image was a bit soft, even in the centre, and
vignetting was obvious (although not uniform in all four corners). This
has me thinking about upgrading to the 2.0/35mm Summicron ASPH.
According to Erwin Puts, there is a significant difference between the
newest lenses and the older ones especially at full aperture and close
distance. I would like to hear from someone who has upgraded from the
old to the new Summicron--did you experience a visible quality
(sharpness) improvement? Third, with the 75mm and 90mm lenses, the
improvement when stopping down from full aperture was much less
pronounced and hardly visible with the 90mm Elmarit-M (just bought in
Bonn in September). In general, based on this limited test, I have
concluded that the 90mm Elmarit-M is sharper than the 75mm Summilux--but
on the other hand the Summilux gives an incredible image quality
considering the f1.4 maximum aperture.

Nathan

- --
Nathan Wajsman
Overijse, Belgium

Photography page:  http://members.tripod.com/~belgiangator/index.html
Motorcycle page:
http://www.geocities.com/motorcity/downs/1704/index.html