The Ricoh GXR Mount A12 is a lensless unit for the GXR camera and is fitted with a 12.3-million-pixel, 23.6×15.7mm, APS-C CMOS sensor and a mount that accepts M-fit lenses. The unit offers both electronic and mechanical shutter operation so users can choose between the more accurate and the silent for their picture taking, with a shutter speed range that stretches from 180secs to 1/4000sec in mechanical mode, and 1sec to 1/8000sec in electronic mode. In each mode the maximum flash-sync speed remains 1/180sec.
The sensor allows ISO settings of 200-3200, plus a ‘Lo’ option that is presumably in line with ISO 100. Meanwhile, a 256-segment metering array can be tuned for multi-zone, centre and spot measurements.
As with all the GXR lens units, the Mount A12 can output files in JPEG and DNG raw formats, with a maximum image size of 4288×2848 pixels. Movies can be recorded in 1280×720-pixel resolution.
The unit adds just 170g to the weight of the GXR, but obviously the total weight of a usable system will depend on the lens you choose to mount. The mount-to-sensor distance is 27.8mm – as with Leica M cameras – and the mount is happy to accept M and L (via an extra adapter ring) lenses from any manufacturer.
Ricoh supplies a device for checking the compatibility of lenses to be fitted, as heavily retro-focus designs, and particularly collapsible lenses, may actually come into contact with the optical filter covering the sensor. I didn’t have any problems, but Ricoh reports the Leica Elmar 5cm f/3.5 and the Hologon 15mm f/8 as incompatible.