Kuribayashi's 35mm SLR system based on a proprietary breech-lock bayonet mount with support for automatic diaphragm.
The cameras of this system can be divided into four major categories:
- PENTA V, V2 (aka FLEX V), V3 (aka V3 FLEX), V6, V6 II - basic fully mechanical SLRs with a quick-return mirror, focal plane shutter with speeds ranging from 1/2 to 1/500th of a second, fixed pentaprism viewfinder with split-image or micro-prism ("Micromatic") focusing, and a self-timer. These cameras did not have a built-in exposure meter, however, starting with the V3, an accessory clip-on-and-coupled CdS exposure meter could be mounted. A built-in hot shoe only appeared on the last camera in this category, the V6 II;
- FLEX 7 - a Contarex Bullseye's doppelgänger with a built-in CdS window exposure meter, an extended range of shutter speeds from 1 to 1/1000th of a second, and a built-in hot shoe;
- FT, FT II - models with TTL stop-down exposure metering, match-needle system in the viewfinder, an extended range of shutter speeds from 1 to 1/1000th of a second. A built-in hot shoe only appeared on the FT II (it certainly looks like Petri's mark "II" was reserved for cameras with marginal improvements that buyers had to pay a higher price for);
- FT EE, FTE, FA-1 - models with TTL open-aperture exposure metering, match-needle system in the viewfinder, shutter-priority auto exposure mode with manual override. For some reason, both the FT EE and FTE models again received Petri's "classic" shutter speed range from 1/2 to 1/500th of a second, while the FA-1 had an extended range from 1 to 1/1000th of a second.
A fairly wide range of lenses was released for the system. It allowed a photographer to shoot a wide range of subjects: from landscapes and architecture to casual, portrait and wild nature photography. The lenses of this system can be divided into three major categories:
- C.C Auto Petri - lenses with automatic diaphragm;
- EE Auto C.C Petri - as the plain "Auto" lenses, but with "EE" (Electric Eye) setting for shutter-priority auto exposure mode with the FT EE, FTE and FA-1 bodies;
- C.C Petri - preset lenses that perfectly existed SIMULTANEOUSLY with the "Auto" lenses.
In the lens names, "C.C" simply means "combination coated" or "color-corrected", or both at the same time.
As in the case of Orikkor screw mount lenses, it is unlikely that Kuribayashi (renamed to Petri Camera Co., Inc. in 1962) was engaged in the production of all optics for this system. Most likely, some lenses were developed and produced for Petri by companies such as Sun and Tokina.
In the 1970s, Petri cameras were technologically inferior to models from major manufacturers equipped with electronically controlled shutters, interchangeable finders and focusing screens, motor drives, hundreds of accessories, etc. Unable to withstand the competition, Petri filed for final bankruptcy in 1977.