The Calumet 6×7 Roll Film Holder C2 lets one to shoot 120 medium format roll film with a large format camera (a monorail, a field camera, etc.) that is designed to use 4×5 sheet film. A near analogy of this in today’s digital world would be the “crop mode” in certain full-frame DSLRs. One advantage of using such roll film holder is to have the flexibility in perspective controls of a typical large format camera because most medium format systems (except for rare breeds like the Fuji GX680) lack such features. Even perspective controls are provided with tilt-shift lenses in the system, the movements of such lenses would be very limited in comparison with a monorail. Another advantage is of course, with the sacrifice of the ultimate resolution of large format film, the convenience of having multiple frames on a roll and cost per frame would be greatly reduced. A roll film holder that shoots 6×7 will give 10 frames per roll (8 frames/roll for one that shoots 6×9). Even a 6×12 holder, with a frame coverage equivalent to half of a 4×5 sheet, still gives 6 frames/roll. Moreover, depending on the size of the enlargement, the sacrifice in resolution might not be as critical as one might expect. Below is an example taken with 120 format Ilford HP5+ (exposed at ISO250, regular development in DD-X) using a Schneider Super-Angulon 75mm f5.6 on a Toyo-View C monorail camera. The second image is a 100% crop of a 2400dpi scan of the original 6×7 frame.
Unlike roll film backs from Linhof or similar ones from Horseman, the Calumet C2 does not require the removal of the ground glass from the camera. Instead, it is designed to be inserted into the camera just like an ordinary sheet film holder. This makes the shooting process much easier. Below is a snapshot of the my Calumet C2 in action.
However, this convenient feature does come with a price. As shown in the photo below, both the taking and feeding reels are located on the same side of the holder inside a single housing in order to create the “thin” portion of the holder so that it can be inserted into the camera. This design makes the path that the film travels from the feeding reel to the taking reel much longer than the Linhof and Horseman holders, which risks losing the first frame of the roll (out of 10 or 8). Also, all the extra rollers, springs, and gears required for this design to function would give more chance for the film transport to malfunction when the holder ages.
Other than that, the Calumet C2 remains an indispensable piece of accessory for any large format shooter who wants to expand the functionality of their camera by using 120 roll film and on the other hand keeping operation as simple as possible. Let’s look at one more sample image which was also taken with HP5+ (again exposed at ISO250 and developed in DD-X as directed from chart) using the Super-Angulon 75mm f5.6. Note that the original 6×7 frame was cropped to 2:3 ratio.
Finally, one thing worth mentioning is the Calumet C2 also accept 220 film as shown by its mechanical frame counter and there is also a newer model called C2N which is lighter (by using plastic parts) and with a different internal film winding mechanism.