This was my first time using medium format camera and the first time me hearing about medium format.
Medium format has traditionally referred to a film format in still photography and the related cameras and equipment that use that film. Generally, the term applies to film and digital cameras that record images on media larger than 24 by 36 mm (full-frame) (used in 35 mm photography), but smaller than 4 by 5 inches (which is considered to be large-format photography).
In digital photography, medium format refers either to cameras adapted from medium format film photography uses, or to cameras making use of sensors larger than that of a 35 mm film frame. Often, medium format film cameras can be retrofitted with digital camera backs, converting them to digital cameras, but some of these digital backs, especially early models, use sensors smaller than a 35 mm film frame.
While at one time or another a variety of medium format film sizes were produced, today the vast majority of medium format film is produced in the 6 cm 120 and 220 sizes. Other sizes are mainly produced for use in antique cameras, and many people assume 120/220 film when the term medium format is used.
The general rule with consumer cameras is the more cameras sold, the more sophisticated the automation features available. Medium format cameras made since the 1950s are generally less automated than smaller cameras made at the same time, having high image quality as their primary advantage. For example, autofocus became available in consumer 35 mm cameras in 1977, but did not reach medium format until the late 1990s, and has never been available in a consumer large format camera.