Chapter 2
Leica R-Lenses
6
At aperture 1.4 the overall contrast is medium, as can be seen
from the graph, where the low frequencies are below 95%. The
important 20 Lp/mm are clearly defined with 60% in the center
and 40% in the outer zones. The edge sharpness is a bit soft as
can be seen from the low position of the line for the 40Lp/mm.
High contrast scenes with many light sources and deep shadow
areas are reproduced with a slight veil of softness, but quite
low halo around bright spots. You will use the wide aperture of
1.4 to capture scenes in low light situations that are intere-
sting, moving or informative-documentary in character. For this
kind of photography, the Summilux is eminently suited. The per-
formance wide open is better than can be captured on modern
high speed emulsions . Stopped down to 1:2 the overall con-
trast improves visibly, as internal reflections are effectively
reduced.
Aperture 2.8 again improves contrast and now performance in
the center is very high. In the outer zones the quality lags a bit
behind, but for this type of photography that is not so impor-
tant. Here you should look at the 20 Lp/mm as the guiding line.
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Aperture Stop 1.4
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Y'[mm]
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Aperture Stop 2.8
