56 x 56 mm image area · 1 interactive lens diagram
Hasselblad V, Rolleiflex, Bronica SQ, Mamiya 6, and other square roll-film systems | Nominal 56 x 56 mm film image area with a 79.2 mm diagonal
6x6 is the square 120 roll-film format associated with many classic medium-format systems. The name is nominal; the usable image area is typically around 56 x 56 mm. Its square frame lets photographers compose without rotating the camera and decide later whether to crop vertically, horizontally, or keep the square, which made the format especially important in studio, portrait, wedding, and editorial work.
Lenses for 6x6 must cover a larger diagonal than 645, and the square frame means all four corners are equally important rather than being hidden by a narrower rectangle. Normal lenses are commonly around 75 to 80 mm, with wide angles and fast lenses becoming large quickly. In the catalog, 6x6 entries help show the optical priorities of square-format systems: generous coverage, even field performance, and mechanical packaging for waist-level SLRs or compact medium-format rangefinders.