The OM system is a single-lens reflex camera system from the Japanese company Olympus.
In the early 1970s, the first model with interchangeable lenses was introduced. Thus began the success story of the system. Countless other cameras, an extensive lens park, and numerous accessories, flash units, bags, motor drives, and more followed.
Between 1972 and 1997, a double-digit number of different models were developed for the system. Officially, only the models with a single-digit designation belong to the OM system, as only they are 100% compatible with the available accessories.
In 2012, the Olympus OM-D, the first digital camera, followed.
More about the history of the system at olypedia.de.
Overview of the available exposure modes of the OM models.