Polaroid 4x5 back for pack cameras

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This is a replacement back for a Polaroid pack film camera that allows it to shoot 4x5 negatives using the included custom film holder which is only 106mm wide, so that this film back will fit onto the back of the camera flush. Remove the hinge assembly from the Polaroid camera, along with both the film and battery doors. Print the back with supports everywhere, file the half circle for the tripod socket, and a small slot on the bottom left hand edge to fit. You'll need to file the latch hooks to fit. Open the latch when fitting it to avoid putting pressure on the latch hooks when mounting. Drill two holes on the left bottom edge to match the rivet holes in the camera body, and mount the back with two small screws. Line the inside film plane with black felt. Since the film plane is offset 18mm to the rear, the lens body will need to be moved to the rear. Spacers are included to help with this job, which involves removing the shutter/lens body and moving it back with the spacers, remounting it with a 3/16" rod through the spacers. Glue a 38mm wide piece of felt at the film holder opening. You may need to shim it with cardboard to provide an adequate light seal once the pressure plate is on. Cut dark slides from bristle board (heavy poster paper) and make sure they slide OK right into the end slot. Tape on the pressure plates with hockey tape with the wide part facing outwards at the film entrance to provide support for the dark slide.