Leica S-ADAPTER C Notice D'utilisation page 19

B. Exposure metering
All three metering methods - multiple field, center weighted and spot -
are available.
Note:
The aperture dial on the Contax 645 lenses has no function when used
on Leica S models with the adapter and the value set on the dial has no
effect. The aperture is selected using the setting dial on the camera, in
both manual and aperture priority mode.
c. Exposure modes
All four modes - automatic program (P), shutter priority (T) and
aperture priority (A), manual control (M) - are available.
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