Hi all:
Our OLY FAQ doesn't have any lens testing info from Popular Photography. I
always considered there tests superior to Modern Photography. So I took a
look at some published lens test data from the 1980's. In order to make the
data most meaningful, I reworked their numbers for " ontrast of a 0.01mm
silt image" (herein called contrast values) into relative values. My relative
values reflect the 0f the highest ever measured reading for all tested
lenses in the same focal length and aperture class. (I used the high values
reported in the April 1984 issue.)
Since Popular Photography measured at the center, 1/3rd out, 2/3rds out, and
the far edge, I have calculated relative values for each of these distances,
plus the following f stops: 1.7 to 2.0, 2.8, 4.0, 5.6, and 8.0 There maximum
contrast values for the 50 mm f/1.7 to 2.0 class of lenses are:
Aperture Center 1/3rd out 2/3rds out Far edge
1.7-2.0 70 60 50 50
2.8 81 75 59 60
4 85 85 70 75
5.6 85 86 77 81
8 84 85 79 81
Note that no one lens ever achieved this! For instance, a lens like the Zeiss
Planar T* f/1.7 has its highest values in the center of the field and the
Leitz Summicron-R f/2.0 has them at 1/3rd out. So each make is a design
compromise.
Now, let's answer the questions: Is the Zuiko 50mm f/2.0 macro superior (based
on the slit image test method) to the Leitz Summicron-R 50mm f/2.0 and how do
they compare to the Zuiko MC 50 mm f/2.0 4 element group (latest) design? I
could make additional comparisons to the Zuiko f/1.8 5 group design, f/1.4,
1.2, 3.5, as well as most any other major 50 mm lens of that era, but the
library didn't have test reports before 1980 AND I'm not a glutton for
punishment. But if anyone wants to find the Popular Photography normal lens
comparative test from the late 1970's and give me the values for the Zuiko
f/1.4, I'll post a follow-up comparison to the Zeiss Planar T* f/1.4
To cut to the chase and pique your interest, let me say that the Zuiko f/2.0
macro is, for most practical purposes, equal to the Summicron-R in relativized
contrast values. It beats it in the 0.000000lare department with a 0.45% vs.
0.85%
in the Summicron-R and 0.87 0n the Zuiko f/1.8. It also beats it in the
distortion department with none, vs. very slight barrel in the Summicron-R and
slight barrel in the Zuiko f/1.8
Here is the data for the three lenses. These are based on measurements at
infinity. (The Zuiko macro was 10 (center) to 40% (far edge) lower at 1:2
magnification). I've added my percentage values in parenthesis, next to
Popular Photography's contrast values. Remember, a 100 in parenthesis means
it that combination of aperture and position on the film is the best showing
for any lens of this type tested by Popular Photography up through April 1984.
Zuiko f/2.0
Aperture Center 1/3rd out 2/3rds out Far edge
2.0 69 (99) 58 (97) 50 (100) 51 (98)
2.8 73 (90) 61 (81) 59 (100) 55 (92)
4 80 (94) 79 (93) 65 (93) 69 (92)
5.6 85 (100) 84 (98) 70 (91) 76 (94)
8 84 (100) 85 (100) 76 (96) 80 (99)
Zuiko f/1.8
Aperture Center 1/3rd out 2/3rds out Far edge
1.8 60 (86) 50 (83) 35 (70) 50 (100)
2.8 77 (95) 70 (93) 45 (76) 55 (92)
4 83 (98) 80 (94) 52 (74) 70 (93)
5.6 84 (99) 86 (100) 69 (90) 71 (88)
8 83 (99) 85 (100) 76 (96) 76 (94)
Summicron-R f/2.0
Aperture Center 1/3rd out 2/3rds out Far edge
2.0 65 (93) 56 (93) 40 (80) 50 (100)
2.8 80 (99) 75 (100) 50 (85) 55 (92)
4 83 (98) 85 (100) 70 (100) 73 (97)
5.6 85 (100) 86 (100) 77 (100) 72 (89)
8 81 (96) 84 (99) 77 (97) 71 (88)
My conclusions from this are that the 50 mm f/2.0 Zuiko is superior to a 1984
era 50 mm f/2.0 Summicron-R, based on a combination of focusing range, image
quality (as measured by the slit image test - which, taken alone, makes them
equals), distortion, and flare. The Summicron is 20 percent lighter and the
f/1.8 Zuiko is about 45 0ghter. That is a negative when packing lots of
lenses. Another conclusion, the Zuiko macro at f/2.0 is as good as a 50mm
f/1.7 to 2.0 class lens gets when used wide open! (But, for example, it
doesn't beat a Zeiss Planar T* f/1.4 used at f/2.0). And finally, the Zuiko 50
mm f/1.8 is one heck of a lens at f/8.
A final caveat: there is possibly a statistical problem here with my use of
percentages of percentages. And the ever present problem with sample size!
Hope this was/is useful to some not yet turned off by normal lens comparisons.
I was basically backing up my statement that to a Leica M6 user, the OM-4Ti or
OM-3Ti with a 50mm f/2.0 macro is "Leica-land."
Gary (glad he got his Summicron equivalent) Reese
Las Vegas, NV
P.S. This exercise refreshed my memory that the close focusing aberration
correction in the Zuiko macro decreases focal length as magnification ratio
increases. It is a 40 mm lenses at 1:2 !! That might be considered to be a
shortcoming of this feature.
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