Medium format cameras are often grouped by their frame shape rather than by brand, and 645, 6×6, and 6×7 are the three shapes a curious digital photographer is most likely to run into first. Each one trades frame count, aspect ratio, and handling differently, which matters more than it might seem when choosing a first medium format camera. This guide breaks down what genuinely separates the three.
645: The Shape Closest to What You Already Know
The 645 format produces a rectangular frame reasonably close in proportion to a standard 35mm frame, just considerably larger, which makes it the easiest of the three to adjust to for someone coming from 35mm film or a typical digital camera. It also gives the most frames per roll of the three formats, generally making it the most economical choice per shot and the most forgiving for someone still building confidence with medium format metering and handling.
Bodies built around 645 also tend to be somewhat lighter and more compact than cameras built around the larger 6×6 or 6×7 frame, since a smaller frame generally allows a more compact mechanism, which is worth factoring in if you plan on carrying the camera for an extended outing rather than shooting from a fixed position.
6×6: Removing the Orientation Decision Entirely
A square frame has no portrait or landscape distinction, which fundamentally changes how you compose since there is no decision to make about turning the camera on its side. Some photographers find this freeing, since it removes one variable from every composition, while others find the square shape limiting for subjects that clearly want a wider or taller treatment.
Many classic 6×6 cameras use a waist level finder, which changes handling considerably compared with an eye level finder, requiring you to look down into the camera rather than up through it, and often showing a reversed image that takes practice to compose with quickly.
6×7: Fewer Frames for a Format Built Around Printing
- Produces a wider rectangular frame proportioned closer to a common print size than either 645 or 6×6.
- Gives the fewest frames per roll of the three, generally around eight to ten depending on the specific camera.
- Often found in bodies built for deliberate, planned work such as studio portraiture, where frame count matters less than final print proportion.
- Tends to come in heavier, bulkier camera bodies than either 645 or 6×6 due to the larger internal mechanism needed.
How to Actually Choose Between the Three
If you want the gentlest transition from 35mm or digital habits and the most frames per roll to practice with, 645 is the most practical starting point. If you are drawn to the square format’s distinctive look and do not mind a waist level finder’s different handling, 6×6 offers a genuinely different creative constraint worth exploring on its own terms, similar in spirit to how a half-frame camera reshapes composition habits in the opposite direction by going narrower rather than wider.
If your main interest is large, high quality prints with a flattering proportion and you are comfortable with fewer frames per roll and a heavier camera, 6×7 is worth the tradeoff. None of these choices is permanently binding, since many photographers eventually own cameras in more than one of these formats once they understand their own preferences better through actual use.
A Few Practical Notes Before Buying Into Any of the Three
Lenses, backs, and accessories are generally specific to a camera system rather than interchangeable across formats, so committing to 645, 6×6, or 6×7 is really committing to a specific camera system’s whole ecosystem rather than a frame shape you can simply switch on the same body. Research the specific system’s lens availability and secondhand market before committing, and apply the same general warning signs for buying a used camera to any body you consider, since a format with a thin secondhand market can make finding additional lenses later more difficult than the frame shape itself would suggest.
Renting or borrowing a body in each format before buying, if that option is available to you, is the most direct way to judge handling and composing comfort, since written descriptions of waist level finders and frame shapes only go so far compared with actually holding and shooting a camera in each format for a session.
Frequently Asked Questions
No, all three use standard 120 roll film. The difference comes entirely from how each camera masks and advances the film to create its specific frame shape.
645 is generally the easiest transition, since its frame shape is closest to familiar 35mm proportions and it gives the most frames per roll to practice with.
Generally no. Lenses and other accessories are typically specific to a camera system rather than interchangeable across different frame shape formats, even when both use the same 120 film.
It removes the portrait versus landscape decision entirely, which some photographers find freeing and others find limiting depending on the kind of subjects they typically shoot.
The Short Version
645, 6×6, and 6×7 all use the same 120 roll film but differ in frame count, aspect ratio, and handling. 645 is the easiest transition with the most frames per roll, 6×6 removes the orientation decision with a square frame, and 6×7 trades frame count for a print friendly proportion in a heavier body.