Special Features - Leica SummArIt-S 1:2.5/70mm ASPH Notice D'utilisation

Special features

The LEICA SUMMARIT-S 70mm f/2.5 ASPH is a lens designed for the Leica S SLR system.
Due to the 30 x45 mm sensor size of the Leica S cameras it is comparable to a focal length of
28mm with 35mm format systems.
The LEICA SUMMARIT-S 70mm f/2.5 ASPH delivers excellent contrast and resolution across
the entire image field, even at full stop.
The slightly lower contrast in the extreme corners of the image at full stop can be increased
noticeably by stopping down to 5.6. This excellent imaging performance is avail able over the
entire setting range right up to the close up limit of 0.5 m.
The vignetting, characteristic of any optical system, is a maximum of 1.4 stops at full stop in
the infinity setting, and only 1 stop in the close up setting. Stopping down to 5.6 reduces it
to the natural vignetting only. The maximum distortion is very low at just 1.2 % in the infinity
setting and with the shortest distance setting and in practical terms is only perceptible in the
image with exceptionally critical subjects.
A total of 8 lenses are used to achieve this exceptional performance. Their construction is
a modified double-Gauss type, supplemented by two additional lenses. In addition, a fixed
front/protective filter is an integral element of the overall optical system. Four of the lenses
are made of glass types with anomalous partial dispersion - one of these is based on a glass
type originally developed in the Leitz glass laboratory. As a result, the lens demonstrates only
very slight chromatic aberrations right up to the close up setting. In addition, highly refractive
glass types are used to minimize monochromatic aberra tions.
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