How-to: Shoot 120 & 35mm film in a Polaroid pack film camera

After using a Polaroid pack film camera to shoot paper negatives, I was wondering how easy it would be to shoot other film types. The closest size native to the Polaroid is 120 film, so it made sense to explore that option. I’ve seen other conversions to 120 using existing commercial 120 backs adapted to the camera (which can be hard to find), or alternate 3D printed backs (which look pretty clunky). So the question is, could it be done in a simple, inexpensive way that retained the look of a Polaroid camera?

Here’s how this article breaks down:

Step 1: Will 120 film fit?

Spoiler alert: my first step was to see whether a 120 film roll would actually fit inside a Polaroid camera with the back closed.

Nope. But how about with the rollers removed?

I did some surgery on a spare back, removed the rollers and was surprised to see that it fit! I quickly designed a 6×6 film holder the size of a Polaroid film cartridge, along with the roll adapters, printed it on a 3D printer, and popped it into the pack camera. With the rollers removed, it fit fine!

The next step was to design the film pressure plate and a film advance mechanism. The pressure plate would have a hole lined up to show the 6×6 exposure number on the film’s backing paper. The film advance knob would just be a shaft that fit into one of the spool adapters.

Simple!

6×6 here we come!

I put a mock roll of 120 film into the adapter, put on the pressure plate, installed the knob, and marked the locations where the knob enters the camera as well as where the exposure number peephole was located. The next steps required commitment: I filed a hole in the side of the camera and back for the film advance knob, and drilled a hole in the back for the peephole. After installing the adapter, I found I couldn’t advance the film. It looked like the camera back was putting pressure on the 120 spools, preventing them from spinning.

I really wanted to make this work, so I marked where the spools were hitting the inside of the back, took out my Dremel and cut grooves for the spools so they could spin. This gave enough clearance for the spools, and the film advanced freely! This was getting exciting! Later, I would end up designing a 3D printed back that replaces the Polaroid back so it wouldn’t need to be hacked up to make it work.

I loaded a roll of 400-speed film into the cartridge, set the film speed on the Polaroid for 300, advanced to the first frame and headed out. Using the Polaroid was fun as always, though I had to remember to advance the film after taking the picture. I got home, developed the film, and couldn’t believe how well it worked!

The scanned negatives showed sharp detail and although the negatives were a little thin, they were consistent (I later learned Arista 400 should be shot closer to 200).

I thought 6×6, or maybe 6×7 would be the largest format that would fit into the size of a Polaroid cartridge since the spools are on the edges and there simply isn’t room for anything bigger. Or is there?

The only way 6×9 would work is to move the film spools toward the center, forcing the film to take a >220° turn at each end so that a full 9cm wide frame could be exposed horizontally. This was much easier said than done.

Yep, 6×9 wasn’t as easy…

I designed a 6×9 cartridge and pressure plate and tried it out with a dummy roll of film. There was a LOT of friction. The ideal solution was to put a bearing on each rotating surface, but that would be overly complex. So I sanded each rotating surface with 600 grit sandpaper and made sure each surface that the film passed over was smooth. This helped immensely with the dummy roll, so I loaded a roll of 120 film and headed out. The film advanced fine, until I got to exposure 5. It got harder and harder to turn until the 8th exposure was impossible to advance to the end. I had to pull the film out of the camera in the darkroom to develop it, but I was super impressed with how well it worked! The 3 element glass lenses these Polaroid cameras were outfitted with produce pretty sharp pictures with great contrast.

I had some problems to solve.

The film wind-on knob snapped since it was only made of PLA and 3d printed in a direction that doesn’t make it very strong. I ended up using a 1/4″ bolt with a notch cut into the end to connect it to the drive spool. I heated up the bolt head and sunk it into the plastic knob and now it’s pretty much unbreakable. The friction was taken care of by shimming the pressure plate around 1mm from the cartridge to give room for buckling film to pass under. I think the tight turns the film was taking was creating space between the film and the backing paper. Confident these problems were addressed, I headed out again to take some pics, developed the film, and again, was impressed with the results.

6×9 worked on a Polaroid!

Except for what looked like light leaks on some of the pictures…

It seemed to be coming from the exposure counter peephole, maybe caused by the extra space under the pressure plate. For now, I fixed this by making a peephole door that remains closed until I advance the film — in the shade.

Can it shoot 35mm too?

It seemed I was on a roll (literally!) with roll film. If I could make a Polaroid use 6×9 120 film, how about 35mm panorama format? It ends up that the 6×9 cartridge would work well as a template, so the design would be similar, but three problems would need to be addressed: the bigger diameter of a 35mm canister, the method of rewinding it back into the canister, and figuring out how far to advance the film for each exposure.

It was clear that the existing Polaroid back wouldn’t work because of the size of a 35mm canister, so I designed a replacement back with enough clearance to make it fit. Of course, the downside of this plastic back is the weakness of the latch hooks and hinges. For now, I’m pretty careful opening and closing the back, but it seems to work fine and seal out the light.

The problem of rewinding the film back into the 35mm canister was a little daunting, so I ended up simply using another 35mm canister as a take-up spool. This would require attaching the unexposed film to an 8″ leader taped to the take-up spool and feeding it through the cartridge like the 6×9 format. It’s a little fiddly, but it looked like it would work. I bulk load my own film, which allows me to tape the bulk film to the source canister on only one side with masking tape so it would break off at the end of the roll and roll into the take-up spool.

If commercial film is used, this wouldn’t be possible, and you would have to unload the film in a changing bag or darkroom to prevent losing the last couple of frames. The long 8″ leader prevents wasted film at the beginning of the roll, since while loading, the film has to make its way through the cartridge and would get exposed.

Figuring out how far to wind the film after each exposure wasn’t too difficult. I got a test roll of 35mm film, set it up in the cartridge, then counted how many winds it took to get it to the next frame. Then, I wrote up a chart indicating how many winds to the next exposure and cut a piece of paper so it had 13 tabs of which I would rip off one when I took a picture so I could keep track of which exposure I was on.

I’ve never shot 35mm pano format photos and was wondering what kind of pictures to take. In a way, it’s not really panorama focal length since I’m still using a 114mm lens, but it is a panorama crop. So I loaded the camera and set out looking for long or tall subjects. It was kind of fun hunting for panorama photos in Banff, and I ended up shooting the 13 exposures quickly. Again, I was pleased with the results, complete with sprocket holes and exposure numbers. And even more pleased that a Polaroid pack film camera can take this sort of photo!

Some scratches crept into some of the photos, and I spent lots of time trying to find out where they came from. I thought it might be one of the surfaces of the cartridge that the film ran through, or maybe dirty capsule felt, but it ended up being the camera bellows themselves. Sometimes I would fold the bellows in and advance the film, which would drag across the bellows and get scratched.

Note to self: advance the film when the bellows is extended!

Wrapping up

It’s been quite the journey! My Polaroid pack film cameras went from being film orphans destined to the display shelf to being very capable medium format cameras. And not only do they take great photos; they often elicit a remark from passers by who either remember these old cameras or think they’re pretty retro cool.

Polaroid i-type film, Instax wide film, paper or lith negatives, 120 film, 35mm film… Now my biggest problem is deciding which camera/format to use when heading out on an expedition, which isn’t such a bad problem!

~ Jim