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Ricoh K (P) system


Ricoh's 35mm SLR system based on the modified Pentax K mount with support of shutter-priority and programmed auto exposure modes. The only difference from the original mount is the addition of a small pin to signal that the aperture ring is set to the "P" position (automatic diaphragm control). However, mechanical compatibility was lost due to this additional pin: when a "P" lens is mounted on a Pentax camera, the pin enters the screw drive autofocus shaft and the lens becomes jammed on the camera.

NOTE: we decided not to record Rikenon P zoom lenses, as most of them were rebranded lenses from such third-party manufacturers as Cosina, Sigma and Tokina. Some of Rikenon P prime lenses were also Cosina rebrands.

Camera lineup

Pentax K mount lens lineup

Wide-angle prime lenses
2.8 Ricoh Rikenon P 28mm F/2.8 ⌀52 1984 
2.8 Ricoh Rikenon P 28mm F/2.8 Macro ⌀49Rebranded lens 1991 
2.8 Ricoh Rikenon P 28mm F/2.8 ⌀52 1997 
2.8 Ricoh Rikenon P 35mm F/2.8 ⌀52 1984 
Standard prime lenses
2.0 Ricoh Rikenon P 50mm F/2 ⌀52 1984 
1.7 Ricoh Rikenon P 50mm F/1.7 ⌀52 1984 
1.4 Ricoh Rikenon P 50mm F/1.4 ⌀52 1985 
Macro lenses
3.5 Ricoh Rikenon P 100mm F/3.5 Macro ⌀491:2 @ CFD 0.43mRebranded lensPro 1996 
2.8 Ricoh Rikenon P 105mm F/2.8 Macro ⌀521:1 @ CFD 0.35mRebranded lensPro 1985 

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