In 1980, Leica introduced the R4, with an attractive new body design and additional features absent in the previous R3. Production lasted until 1987. Main features of the R4 include:
1. Very compact, intuitive design.
2. Spot manual; spot aperture-priority; averaging aperture priority; shutter-priority, and program modes.
3. Shutter speeds from 1 second to 1/1000 sec.
4. Exposure compensation, 2 stops above or below in half-steps.
5. Depth-of-field preview lever.
6. Electronic self-timer, can be aborted.
7. User-interchangeable focusing screens.
8. Accepts a compact, well-designed motor-drive.
9. Leica R4s (1983): budget model lacking shutter-priority and program modes.
10. Leica R4s, model P, or model 2 (1986): similar to R4s, with minor improvements.
In some respects, the technology and features of the R4 lagged behind that of its longer-lasting contemporary, the Nikon F3. While the F3 boasted superior ruggedness, greater range of shutter speeds, interchangeable prisms, and TTL flash, it lacked the R4's beautiful ergonomic design and range of exposure modes, including spot metering. The most significant of these differences were resolved in 1987 with the introduction of the R5.
Leica R4 Owner's Manual
Leica Reflex Photography, by Brian Bower