The Olympus OM-1 is a manually operated 35mm single-lens reflex camera, part of the Olympus OM system.
The very first model was presented at the Photokina of Köln in 1972 and was called the Olympus M-1. Thirteen years earlier, the release of the Nikon F had made the 35 mm SLR the standard choice for professionals accustomed to Leica and other rangefinders, but it had driven the market towards heavy and bulky cameras. The Olympus M-1 changed this and with it began a reduction of size, weight and noise of the 35 mm SLRs. It was designed by a team led by Yoshihisa Maitani, who had already created the Pen and Pen F cameras, noted for their compactness.
Since Leica's flagship rangefinder cameras are known as the M Series, Leica complained about the name of the M-1 forcing Olympus to rename it as the OM-1 to further clarify between the brands. Because of this, today bodies and lenses with the original M name are rare (5000 bodies were made according to Olympus) and sought after by collectors.
The OM-1 is an all-mechanical SLR. It has a very large viewfinder with interchangeable screens but a fixed prism. It also has a through-the-lens exposure meter controlling a needle visible in the viewfinder. It has a very compact body, essentially retained on later models. One novel feature was the decision to locate the shutter speed dial around the lens mount, rather than on the camera's top plate. A significant advantage of this layout is that the camera can remain at the eye far more easily, between shots, than some other SLRs, it also makes it far easier for "left-eyed" users and enables exposure values to be more rapidly adjusted as the shutter operates in the same plane (effectively around the lens) as the aperture ring. It also less fussy to use than a conventional shutter dial, and easy to sense what shutter speed is being set. With practice both aperture and shutter speed can be adjusted at the same time, made easier by their being reasonably close together but distinct in use.
Originally, the bottom plate needed to be modified to mount a motor drive on the OM-1. In 1974, Olympus launched the OM-1MD (MD standing for Motor Drive), to which a motor drive can be attached without need for modification. This new version has a small plate marked 'MD' on the front, and a small circular cover with a coin slot (covering the motor drive coupling) on the underside of the body.
The OM-1n is the same as the OM-1MD with a redesigned film advance lever, a flash ready/sufficient flash LED in the viewfinder, and automatic X-sync regardless of the position of the FP/X switch, when it is used with a T-series flash unit mounted on Flash Shoe 4.
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This article was originally based on "Olympus_OM-1/2/3/4" in Camerapedia, retrieved on 26 May 2006 under the GNU Free Documentation License.