Following the Leicaflex series Leica took a totally new approach; the R3 was developed in cooperation with Minolta and closely based on their XE. Initially manufactured in Solms, Germany, production was later moved to the new Leica plant in Portugal.
In appearance very similar to the Minolta XE using the same electronics, the camera incorporated a Leica developed shutter and modifications to the metering system offering Leica's traditional facility of selective metering in addition to integrated (centre weighted) metering. It was the first Leica SLR camera to offer automatic exposure.
The camera was a commercial success at a very difficult time for the company, sales of the latest rangefinder Leica M5 had been very poor and the previous Leicaflex series had made little or no profit leaving the company in a precarious financial state, the R3's success seemed to indicate a new direction.
For selective measurement the R3 used a secondary mirror with light cell in the base just like the Leicaflex SL. For integrated measurement two light cells were mounted on the viewfinder prism; switching between selective and integrated was electronic.
The Leicaflex camera lenses had either one or two sloping cams for aperture connection. The R3 replaced these with a single "stepped cam" conveying, in addition, the maximum aperture. From then on most lenses were made with all three cams but a few, especially those supplied with R cameras, had only the third stepped cam and were marked "Leica R Only". These lenses had a very small modification to the original bayonet making it impossible to mount them on earlier cameras.