Developer: NIKFI and MKBK (Cinema and Research Institute and Moscow Cinema Equipment Construction Bureau)
Role: Motion picture
Sensor size: Super-35
Flange focus distance: 61mm
Introduced: 1984 — Same source as above
Cameras: Soviet-era Russian 35mm film cameras
Mechanism: Breech lock
OCT-19 is essentially the Soviet answer to PL, with the same four lugs and breech lock ring, though they are not directly compatible. The mount is of most interest for the lenses that were made, most famously by LOMO, the Leningrad Optical Mechanical Association, especially in the 1980s. While old Russian lenses were at one time a low-cost option, the popularity of lenses with what we'll politely call character has made them expensive, particularly the anamorphic options. LOMO, now principally a medical imaging company, is only tangentially connected with the Lomography movement which celebrates a certain analogue “glitchiness” in photography, but the comparison between that and the (rather gentler) artefacts sometimes sought by users of OCT-19 lenses are hard to ignore.
OCT-19 lenses (and to a lesser extent slightly lighter-built OCT-18 types) can be used on shallow-mount cameras with adaptation, although many such lenses have been rebuilt to PL or other mounts. There are 35mm film cameras from Konvas and others with OCT-19 mounts.
Role: 35mm SLR stills
Sensor size: Full frame 35mm
Flange focus distance: 46.5mm
Cameras: Nikon F and all Nikons to date, with updates
Nikon Series E 100mm lens with 3D printed gear
Nikon's long-lived mount gets a mention here mainly because of the popularity of lenses from the company's more mechanical era of still photography. Nikkors from what's often called the pre-AI period enjoy fully mechanical controls, often a sturdy all-metal build, with even the low-cost Series E (for economy) lenses from the 80s featuring more metal than the most expensive modern types. The focus scale is often not ideal for photography, but they're far from the worst option out there and the mount is so deep that the lenses can even be adapted to EF cameras. The mount itself is a bayonet twist-lock broadly similar to EF, Pentax K and others, and has been significantly updated with a complex web of compatibility and capability on various cameras, which should be double-checked before relying on older Nikon F lenses with modern stills cameras.