When you say “medium format” to people*, they probably think of 120 or 620-format roll film. But the definition of “medium format” also includes sheet film larger than 35mm and smaller than 5×4″. Until now I’ve only really used roll film but for my birthday I was given a sheet film camera and I also decided to purchase some sheet film holders for my roll-film cameras such as the Horseman 980 and Mamiya RB67.
* Excludes normal people 😉
It turns out there are lots of very similar sizes of slightly different dimensions, and it’s important to get them right. Here’s my summary.
|Roll / sheet?||Known as||Size (mm)||Size (in)|
|120 roll||6 × 9||56 × 84 mm||2.2 × 3.3 “|
|Sheet||6.5 × 9||63.5 × 88.9 mm||2.5 × 3.5 “|
|Sheet||2¼ × 3¼||57 × 82 mm||2.25 × 3.25 “|
Now for the notes and caveats.
- The dimensions given for sheet film are the actual size of the sheet of film. Depending on the camera and film holder, the image is usually smaller, leaving a margin.
- The dimensions given for roll film are the size of the image. 120 roll film is actually 61mm wide, but you lose a few millimetres with the margin. The width of a 6×9 frame varies depending on the camera.
- Despite my recent blog post about cutting down 120 roll film to make 6×9 sheets, it seems that this wasn’t the right size and my Ensign Cameo actually takes 6.5×9 sheets. My sheets rattle around in the film holder.
- It seems that the 6.5×9 size is predominantly European, while the 2¼ × 3¼ size is predominantly American.
- 2×3 seems to be commonly used to describe any of these sizes, although more often to describe the roll film size
Thanks to this thread for some of the information (as well as various other web sources) which I have merely summarised and tabulated. I hope the information will be useful to someone. If you spot any errors, please let me know.