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Chapter 2
Aperture Stop 2.8
[%]
100
80
60
40
20
0
0
5
10
Aperture Stop 5.6
[%]
100
80
60
40
20
0
0
5
10
The graphs for 2.8 and 5.6 indicate an improvement for the
20Lp/m and the 40Lp/mm, but the jumps are quite small.
Compare the jumps in performance of the Summilux. The resi-
dual aberrations of the Apo-Summicron are already so low at
full aperture that stopping down only improves the depth of
field. At smaller apertures the internal reflections are reduced
15
20
Y'[mm]
15
20
Y'[mm]
and the extreme edge rays are blocked. If you look carefully,
you may see the result of the diffraction at aperture 5.6: the
overall contrast for the 5Lp/mm is slightly reduced compared
to the values at 2.8.
Relative Distortion
[%]
5
4
3
2
1
0
-1
-2
-3
-4
-5
0
5
Distortion is low with 1% but may be visible on critical inspec-
tion and suitable subjects. The Summilux is better here.
Leica R-Lenses
10
15
20
Y'[mm]
9
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