A word of warning against Efke (and Foma, Lucky, Shanghai, etc) and cameras like these.
The red window that shows the frame numbers will fog the film through the poor quality backing paper these films feature.
I've had plenty of old folding and box cameras, and they all did this.
The only ones that work well are Kodak, Ilford, and Fuji. At least if you shoot in daylight. Shading the window does not seem to help.
Strange; I've shot heaps of Efke on my 6x17 that has NO red filter over the frame window with no fogging. In fact, it has 3 uncovered windows (one for 6x12, 6x15 and 6x17).