OM-4.
The Olympus OM-4, an improved version of the OM-2, was manufactured from 1983 to 1987. It was introduced at a US$685 list price for the body alone. It was a battery-powered, electromechanically controlled, manual focus SLR with manual exposure control or aperture priority autoexposure. It used a horizontal cloth focal plane shutter with a speed range of 240s (in auto mode) to 1/2000s plus bulb, and flash X-sync of 1/60s.
The OM-4 featured a built-in spot meter [of a narrow acceptance angle, see Canon FTb] (2% of view; 3.3˚ with 50 mm lens) and was the first camera capable of measuring eight individual areas and averaging them. The light meter used a dual-concentric segmented silicon photo-diode to provide spot or centerweighted readings. It used a graduated linear LCD for the shutter speed at the bottom of the viewfinder to precisely indicate its readings versus the actual camera settings.
In 1986 the OM-4 was improved to a tougher OM-4Ti (OM-4T in USA) version, with titanium top and bottom plates, improved weatherproofing and high-speed flash sync. This last version was discontinued in 2002.
Consumer-grade cameras.
OM-10.
The OM-10 hit the markets in June 1979 at the same time as the OM-2N. The camera was a 35mm focal-plane shutter aperture priority AE SLR camera with an electronic shutter. Only aperture-priority AE was available with the camera unless the optional manual exposure adapter was installed. This allowed the setting of shutter speeds between 1s and 1/1000s, (bulb mode was also available). The camera was equipped with a fixed pentaprism viewfinder which contained an LED exposure indicator. The finder coverage was measured to be 93%.
Exposure control was aperture priority AE using center-weighted light metering. Film speeds of the camera range from ASA 25 to ASA 1600. Film winding was done by using the film-wind lever located on the top right of the camera. Film rewinding was done manually using the film-rewind crank located at the top left. The camera body measured 136 × 83 × 50 mm and weighed approximately .
OM-20.
The OM-20 (sold in the United States as the OM-G) was essentially a refinement of the OM-10, replacing that model's rather tricky mode switch with one that was easier to use. The OM-20 also had a built-in shutter-speed dial, a mode display in the view finder and a much stronger winding mechanism which permitted it to be used at 5 frames per second on the OM Motor Drive 2. The shutter magnet and release system had other minor design improvements.
OM-30.
Essentially an OM-20 with auto-focus capability. With a normal lens there were lights in the view finder to help the user with manual focusing.
When used with a motor drive or winder unit and the M-In Focus Trigger cord, the lens could be pre-focused on a specific point. As soon as an object moved into that focus zone the camera would trigger a shot.
A special motorised 35-70mm autofocus lens was also available at the time, but is now very rare.
OM-40.
A further refinement of the OM-20 with features that were more of interest to serious photographers. It had a lighter, slightly more modern and ergonomic body design. It also had an early form of matrix metering, and a mirror lock-up facility. This was activated when the self-timer was switched on, a feature still rarely found in non-high-end cameras.
Also known in some markets as the OM-PC, the OM-40 had a program mode that automated the selection of both the aperture and the shutter speed.
OM-2000.
An Olympus model made by Cosina, the OM-2000 was not considered by Olympus 'die-hard fans' to be a 'true OM' camera.
The OM-2000 had a mechanical, vertical-running shutter in contrast to the traditional OM cameras with their horizontal-running shutter. This allowed the OM-2000 to synchronize an electronic flash at 1/125s. Many photographers found this capability an advantage for the use of "fill flash" in daylight.
Prototype cameras.
OM-X.
During the design study of the OM-1, the Olympus design team led by Yoshihisa Maitani had worked on a completely modular camera, like a 35 mm Hasselblad. This camera was built as a prototype, and was called the OM-X.
Lenses.
The OM Series lenses had the aperture control ring located at the front of the lens barrel. This was done to move it away from the shutter speed control, which was a ring on the camera body concentric with the lens mount. OM lenses also featured a depth-of-field preview button on the lens, in contrast to most other SLR camera systems, in which the button was placed on the camera body.
The OM lens was designed to sit 46 mm (measured from the lens mounting ring, or flange) from the film plane. The combination of on-lens aperture control and the generous 'flange focal distance' make OM lenses adaptable (with limited functionality) to a variety of other camera systems – including Canon EOS models – by using a mount-specific adapter.
Prototype lenses.
Manual Zuiko lenses that were never marketed:
Accessories.
Being a system, Olympus made numerous accessories for professional portrait, photo journalism, sport photography and scientific photography.