HowTo: Sprocket Holes

A rather basic How-To on how I hacked a Mamiya RB67 to take a 35mm film canister:

1) Get the barrel of a Biro. Confirm that it fits in to the holes at either end of a 35mm film canister.

2) Cut two short lengths off the barrel. You'll have to eye-ball the lengths. You may want to specifically cut lengths that will put the 35mm film right at the top or bottom of the plate. Mine is a little way down from the top, to make sure the full height of the film was exposed, but also lead to some of my framing not coming out as expected.

3) File slots in to both ends of both of your peices of barrel. The slots mean that you can push the barrel further in to the 35mm canister, meaning it is held in place more firmly. The slots at the other ends should be wide/deep enough to sit on the lugs where the 120 film roll usually goes.

4) Put it all together, and pull the film over the plate, and around the take-up spindle, just like a normal 120 film.

5) Make a mental note of where on the back plate the film is sitting. When taking photos, remember that the image is top-bottom reversed in the camera, so if the film is sitting along the bottom of the plate, it will expose the top of the image you see in the view-finder.

6) As you wind the film on, you may find that the frame-counter does not advance. This means you have to flick the mechanical lever that is usually used to allow you to perform multiple exposures, just to make the camera let you expose a frame. This does then mean you don't have that lock-out protection, so you have to be quite systematic to avoid accidental double-exposures. Other people have reported that the frame-counter still works fine, meaning you don't have to fiddle with the mutli-exposure lever.

7) When the film is finished (I got about 16 exposures on a 36-exposure 35mm film) you need to unload it IN THE DARK, either in a dark room, or with the cartidge in a dark bag. Simply pop the 35mm cannister and the take-up spool off the lugs and manually wind the film back in to the cannister. You might want to practice this bit with a duff film in the light, so that you know what you're doing in the dark.

Hope someone finds this helpful!