Two Nikkorex Sekor Nikon F Mount Lenses - Semiautomatic Diaphragms
Special Nikon F mount cameras: Ricoh Singlex, Nikkorex by Mamiya,
Sears SL-11
Three early Nikon F mount cameras produced by other manufacturers:
SL-11 (Sears Roebuck/Ricoh) - Singlex (Ricoh) - Nikkorex F (Mamiya)
A comparision of the Mamiya 1000/DTL and Nikkorex bodies
Nikkorex Sekor F Mount Semiautomatic Lenses
Although it is fairly common knowledge that Japanese camera maker Mamiya manufactured the popularly priced Nikkorex F camera sold by Nikon, what is not well known is that Mamiya also made at least two models of lenses in the Nikon F mount. Both had semiautomatic diaphragms. That is, the diaphragm stops down to taking aperture automatically when the shutter button is depressed to take a photo. However, unlike Nikon's own Nikkor lenses, the diaphragms of the Nikkorex Sekor lenses had to be "cocked" open for the next exposure by rotating a lever on the side of the lens nearest the lens lock lever. There are believed to be two models of the Nikkorex Sekor lenses, a 35mm f/2.8 and a 135mm f/2.8.
The above photo shows the 35mm f/2.8 Nikkorex Sekor mounted on a Nikkorex F body. The handle of the "cocking" lever for the diaphragm can easily been seen in at the "one o'clock" position of the lens mount. This is not the same individual lens as the 35mm pictured above.
The same lens, viewed from top of camera.
The photo above shows the 135mm f/2.8 Nikkorex Sekor. Again, the "cocking" lever can be seen, at the bottom left. It is believed there were very few of either of these lenses manufactured, and it is unknown what market they were intended for.
Next, the Ricoh Singlex, with Nikon F Mount
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Last updated 7 Feb 2002