|the rollfilm holder in the back of a monorail camera, image by Elmo Alves (Image rights)|
Calumet's holder for type No. 120 film rolls on 4x5" plate cameras is an adapter that can be used almost like a normal plate holder or film sheet holder. It has a 6x7cm image frame, thus allowing to make ten images on one standard film roll. It has NO red window. Therefore it has a smart film advance system with a knurl and a button. The film can be advanced by means of the knurl until the next frame. After exposure the button must be pressed once to unlock the knurl. An analog exposure counter is the third element that makes this rollfilm adapter perfect.
The Calumet adapter is very thick so that it doesn't fit the 4x5" camera backs of Cambos and not the camera backs of many ancient large format cameras. The image at the right shows it adapted to a Black Beauty (4x5" version). Maybe it fits Calumet 4x5 cameras too.