6x17 roll film back structure
Roll film back should have several characteristics. The most important feature is to keep the film, completely flat. This issue is so important that various companies have used various techniques for it. In roll film back, regardless of the lens field curvature error, surface of film, should be flat and perpendicular to the optical axis the lens. Also film should be easily move, and dark slide on the arrival and departure, not allow penetration of light into back roll.
In roll film back dedicated, which is designed for Panoral 617 camera, i put a plate to keep the film as flat. And with the addition of 4 metal rollers, smooth motion film was provided on back roll.
617 roll film back interior design
Another part that I often had trouble with it, is the entry point and exit the dark slide. Especially when that point is located towards the sun. By Using stainless steel with the proper thickness, and calculated the size of the doorway, I managed to fix this problem.
6x17 roll film back, can record the 4 image 6x17 on 120mm film. Replacement frame is by knob motion film, and counting the recorded image, will be, by numbers behind the film. 1-4-7-10 numbers, back the film, shows the No. of recorded images. Film counting window, in a certain way, preventing the penetration of light into the roll film back. In addition to the above, a metal gate, preventing the penetration of light to back of the film, and it can be opened only when needed.
In front of the roll back, grooved edges when the roll film back is mounted to panoral 617 camera, prevents of penetration of light into the camera. Also grooved edges on both the front and rear roll film back, will prevent, of light passing to inside. Two sliding lock will connect the two parts into each other.
Number of Image: 4, 6x17cm image on 120mm film
Counting the number of image: According to the recorded numbers behind 120 films.
Material: Aluminum Alloy 7075
Internal Paint: Anti–reflective black
External color: Semi–gloss black coating
External dimensions: W:220,H:110,D:40 mm