Instructables
Picture of sprocket hole photography
Sprocket hole photography (or full sprocket photography) is the method that exposes the full width of 35mm film, including the sprocket holes, in the exposure. This creates some very unique results and is a fun project to experiment with. In this project I'll show you how to expose 35mm film in a medium format camera to include sprocket holes.

I used the Diana F medium format camera, which has a 52mm2 exposure area, and then made a small spacer from a plastic pen cap to allow a standard roll of 35mm film to be used. The best part about this project is that there are no modifications made to the camera, allowing you to quickly switch types of film used without compromising your camera!

Ready to take your own sprocket hole photos? Let's get analogue!
 
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Step 1: Spacer from pen cap

Picture of Spacer from pen cap
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Most medium format film cameras have a spindle inside for you to wrap the start of a fresh roll of film onto. As you advance the film after each shot, this spindle will wrap the exposed film and will be completely removed for developing. Each new medium-format film roll will have a new plastic spindle inside, so the old spindle  gets transferred to the gathering side when new film is inserted. Always leaving you with at least one spindle inside.

Since 35mm film is shorter than medium format film, there will need to be a spacer on the new film side of the camera to hold the 35mm film in place. I found the easiest way to secure the shorter film in the medium format camera body was by making a spacer from a plastic pen cap from a ballpoint pen. I measured the difference in length between the medium format film (52mm) and the 35mm film, and then added a few millimeters to allow for the cavity in the 35mm roll. If you look into the end of a 35mm roll of film you’ll notice a cavity with a partition, we’ll be shaping our pen cap end to match this profile.

Before trimming the pen cap to length, start with making the profile in the end of the cap. I cut a 10mm slit into the capped end of the pen cap. After ensuring the slit matches the 35mm roll cavity I cut the pen cap to its final length, about 3cm.

Step 2: Loading film

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With the pen cap spacer installed into the 35mm film roll, you can insert the film into the camera.

Loading the film upside down (so the pen cap faces up) makes installation simple, and no modifications to the camera housing are required. Pull a section of the film from the roll and feed it through the slit in the uptake spindle. These spindles have a small tooth inside the slit the catches the medium format film, which can also be used to catch a sprocket hole on the 35mm film. I opted to use a small bit of masking tape to secure the film into the uptake spindle, just in case.

Carefully close up the camera and advance the film by winding. As with all film cameras, you’ll need to advance the film past the portion that’s been exposed to light already. With no indicator it’s difficult to determine how much film to advance, to be safe I advanced the film 5 full rotations of the film winder.

Step 3: How much to wind?

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How will you know if you've advanced enough sprockets to continue?

If you’ve used medium format film before you’ll know that it has numbers and symbols printed on the backside of the film that lets you know when the film has been advanced to the next frame and you can stop winding. You can see these marking and numbers through a small window on the back of the camera.

35mm film cameras don’t use this feature and automatically stop advancing when the next frame is reached. With a 35mm film installed in a medium format camera with no automatic stopping on the wind mechanism, how can you tell when you’ve reached the next frame? There's some clever people over here that have worked that out. I find that the charm of film is sometimes the unexpected, so I don't keep too keen an eye on it. Shooting analog is partly about the unknown.

There are 2 methods to solve this:

Low-tech option:
Low-tech method is to wind about 12 clicks to get to the next frame (12 clicks = 12 sprocket holes)
Pulling the 35mm film over the expose area of the medium format camera I counted about 12 sprocket holes from edge to edge. With the camera back in place, you can use the small red-filtered viewing window on the back of the camera to see the sprocket holes of the 35mm film. After exposing the film simple advance the film using the winder until you count 12 sprocket holes pass the red-filtered viewing window; you’re now ready for the next frame!

Photo buffs already know the trick that red-filtered light does not expose film the same way blue light does, so the red-filtered window on the back of the camera is save to use in this manner. For those that are unsure, you can cover this window with an opaque tape and just count the clicks to the next frame.

Advanced method:
The low-tech method works well, but you can run into problems as the uptake spindle grows larger in diameter as you take more photos; the 12 sprocket hole trick can be wildly out of whack after some time of shooting.

Some brainy folks have figured out out mathematically how many turns of the winding dial to get the most out of your film as you shoot.


You’re now ready to get outside and start shooting all kinds of scenes. Like most film cameras, outdoor shots will work well, and indoor shots will require a lot of light in order to show up.

Step 4: Winding and developing

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winding film at end of roll
After you’ve reached the end of a roll of film, you’ll need to remove the film in an enclosure with no light. This could be under a heavy blanket, or in a dark closet, whatever works for you. The important thing is to not expose any of the film to light.

In a completely dark enclosure, open the camera and remove the uptake spindle and 35mm film canister - they will be connected together as the film has not be wound back into the 35mm canister. Using the winding nipple on the 35mm film canister gently wind the 35mm film back into the canister. When you reach the beginning of the film remove the masking tape holding the film to the uptake spindle and continue winding until the entire film length is inside the 35mm canister.  You should now have a full roll of 35mm film and an empty spindle, ready for the next roll.

developing film
Now that you have a few rolls of film shot it’s time to take them to get developed. Take them to a photo lab and ask them to develop the film into negatives as normal but do not print any of the negatives.

Almost every photo lab will not be able to print your 35mm film to include the sprocket holes. That is because the machines that process the 35mm film to prints have a viewing area that is inside the sprocket holes, and the exact width of one standard frame (35mm has a 3:2 aspect ratio)
While this is fine for normal prints, we want to see the sprocket holes, so we’ll have to make our own prints. Don’t worry, it is super easy.
 

Step 5: Making prints

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After your film has been developed by a photo lab you can take the negatives and reveal those sprocket holes.

I don't have a scanner, and instead of making a light box I made do with an upturned desk lamp with a fluorescent bulb and laid a paper towel over it to diffuse the light.
There is a serious fire hazard if using an incandescent bulb, or any type of bulb that gets hot, with paper towel nearby. Always keep a safe distance from the bulb surface to the paper towel to minimize any chance of a fire, and never leave this setup unattended.

My desk lamp can rotate to race upwards, and there's a nice gap between the bulb and the rim of the shade. I loosely taped a paper towel over the rim of the lamp to create a light table.

Using a tripod to get consistent pictures, I set my camera to 'macro' mode and set up the tripod to point down onto the light table. Almost all point-and-shoot cameras will adjust to the brightness if you half-click the shutter. For those with beefier DSLR cameras, or those savvy enough with their point-and-shoot cameras, you can adjust the white balance to fine tune the lighting.

Lay the negative strip over the light table and start snapping pictures, successively moving the negatives along the light table until you have a picture of the entire strip. I made sure each picture of the negative covered multiple frame exposures, giving me lots of room to crop later in image editing software.

Step 6: Turn a negative to a positive

After taking photos of your negatives it's time to editing them and give them some life.

Take your photos from your camera and put them in a folder on your computer. Most photo editing programs have the basic tools we need: crop, invert, and colour correction.

I've shown the method with the image editor Photoshop, and it's free competitor GIMP

Photoshop:
  • Open file
  • Crop to selected area (C)
  • If your photo is skewed use "transform" tool (ctrl T) to stretch the perspective to cropped area
  • Invert image colour (ctrl I)
  • Edit colours and levels (ctrl U, and crtl L)
  • Resize and save

GIMP:
  • Open file
  • Crop to selected area: Tools → Transform Tools → Crop
  • If your photo is skewed use  "stretch" tool (shift P) to stretch the perspective to cropped area
  • Invert image colour (ctrl I)
  • Edit colours and levels: Color → Levels
  • Resize and save

Step 7: Experiment and have fun!

For me, taking pictures with my medium format camera is about adventure and the unknown. Part of the charm of Lomography cameras is to take experimental photography and challenge yourself. The results are always unique and you can include sprocket hole photography with loads of other low-fi techniques, like multiple exposures or cross processing.

Here's some more samples from my sprocket hole photos. Have fun!



Have you taken your own sprocket hole photos? I want to see it!

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Hey there, nice guide and smart thinking with the pen cap to hold the cartridge. About the red window, you probably know this but it looks like all that red splotches in your images are indeed from opening the filtered window on the back to count sprocket holes. If you've seen redscale photography then you'll know that it's just normal film being shot through backwards so the red layer gets exposed first, and all the filters for the different emulsion layers are out of order, making the image all red. It's still basically just as sensitive to light.

I just wanted to add that because you don't mention it and some people may want to avoid the red streaks by covering their window with thick black tape.

Lei_Kei10 months ago
Nice work!
Throttle7810 months ago
It is a Holga! I only had a used film canister laying around, but when I pick up some new film, I will definitely post some photos!
antoniraj10 months ago
cool... you missed 'r' in you gif (spocket)
Throttle7810 months ago
I was inspired by your pen cap, but realized that it would leave the film not centered in the camera. So to fix this, I took the pen body and cut it so it would be centered. Thanks for the inspiration!
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Uncle Kudzu10 months ago
120 film has a lightproof paper backing for use with the frame counter window. 35mm does not. Looks like you're getting light leaks by not taping over that little window. Of course, some folks like light leaks...

Anyway, your solution for holding the 35 film cassette couldn't be any simpler or cheaper! And your instructable is really well illustrated. I feel inspired to try this with my Holga. Thanks for sharing!
Well, when I saw your reference to Lomography I suspected that you weren't gonna let a little stray light ruin your day :)

Thanks for including the Gimp instructions! And I'll let you know my results when I try your 35mm conversion with my Holga.
joeofloath10 months ago
That gif of you unrolling the film... It makes me cringe so hard.

Cool instructable though.
icekid10 months ago
Awesome guide!