Leica SUMMILUX-M 1:1,4/28 mm ASPH. Notice D'utilisation page 24

STRUCTURE OF LEICA M LENSES
In principle, all Leica M lenses have the same external structure: they have an
aperture setting ring (4), a setting ring for the distance (5) with a finger grip (5a)
and a fixed ring (6) with an index for focusing (6a), a depth of field scale (6b)
and a red index button for changing the lens (6c).
There is also an external thread (2a) on the front mount of the Leica
Summilux-M 28mm f/1.4 ASPH for attaching the lens hood.
The bayonet flange contains a 6-bit barcode lens identification (7), which
transmits lens data to the camera body. This is used to adjust the exposure
metering system on digital Leica M models and to optimize the image data for
the lens type.
FOCUSING
The focus is adjusted by turning the focusing ring (5). The finger grip (5a)
enables you to work quickly and comfortably.
DEPTH OF FIELD SCALE
The scale (6b) on the fixed ring (6) shows the depth of field range available for
the set distance. This is read off using the corresponding lines labeled with the
aperture values.
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