Both commercial and artistic photographers prefer a medium format camera because it exposes a larger area of film, resulting in sharper images that can be enlarged or cropped with more facility. Most people use 35mm film in their personal cameras, which is the physical width of the film, but medium format film is 60mm wide. Using a medium format camera, although heavier and more expensive than a smaller one, allows the photographer greater control over the image.
Since a medium format camera uses 60mm film, the developed image can be enlarged to cover a magazine cover, a poster, or even the side of a building with less graininess or blurring than would result with small film. Larger negatives capture more detail, which reproduces crisper prints. The higher quality also means it's easier to retouch the negatives, correcting blemishes or softening an unwanted glare. Film size is the main motivation for professional photographers to upgrade to a medium format camera.
Medium format film, while having a standard width, doesn't have a standard span. Any roll of 60 mm film, with a length of 120 or 220mm, can be exposed with varying frame spans, unlike standard 35mm film. One popular size for portraiture is 6 x 7, meaning 60mm x 70mm, because it is almost square and allows for cropping to different common proportions. Many magazine publishers prefer photographs of dimensions proportional to a 6 x 7 negative. Some artistic photographers decide to use a square frame of 6 x 6 because it creates interesting compositions. Other panoramic photographers of landscapes or cityscapes expose a huge rectangle of 6 x 12 film with yet another framed proportion, although they may only get ten shots per roll.
A photographer of special events, sports, wildlife, architecture, fashion, or journalism benefits from other accessories for a medium format camera. They can be equipped with exchangeable backs that switch midroll between different types of film without exposing the shots to daylight. For example, with a Polaroid film back one can take a test shot that immediately shows what the real shot will look like. Then, the Polaroid back can be snapped off and replaced with film for a permanent record of the image. Also, there are a wide variety of specialty lenses, such as macro or fisheye, compatible with a medium format camera. Even digital technology has been adapted for use in place of film.