126 Film Pinhole Camera

This pinhole camera took less than half an hour to make. Along the way I came across a 'pi problem' which camera makers have to deal with (see step 13 for my solution).

Building the pinhole camera came about after coming across a 'bargain bin' at a camera shop with discounted items. There were some 126 film cartridges going for a good price as the film had expired 40 years ago. I brought a couple as I thought maybe they could be used to make pinhole cameras. A web search showed that this had been done before and so I followed this design.

Aluminum Beverage Can

Black cardboard

126 Film cartage

2 rubber bands

Drink can tab

Blu-tac

Black tape

Here's a sample of the latest pinhole photos taken with the short camera body, using 35mm film in a 126-film cartridge. As can be seen there are some light leaks as I had forgotten to use the rubber bands to hold the body pressed into the film cartridge. One of the photos was uploaded for International Pinhole camera day.

Cut a length of stiff black cardboard 152 mm long by 38 mm wide, divide the length into four squares a score with a knife to make easier to fold. Next construct an open box by securing the ends with black tape.

Check the open box will fit snuggly into the recesses of a126 film cartridge.

• Cut a sheet of aluminum from and empty aluminum beverage can. Do this by cutting off the top and bottom of the can with a hobby knife and pair of scissors, trim the edges and then cut down the length of the can.
• Fatten the sheet by rolling it against the edge of a table.
• Cut out a rectangle: 58mm by 40mm from the aluminum sheet. Cut a piece of black card the same size.
• Sand the middle of the piece of aluminum to make it very thin.
• Make a hole in the aluminum with a pin. Only just piecing the aluminum. Sand to make smooth.
• Make the center area of the aluminum, black using a black marker.

• Cut out the center out of the black card and glue to the piece of aluminum.
• Mark a cross where the pinhole is to make it easier to find.
• Attach the sheet to the open box with black tape.

• Fit the box to the 126 film cartage.
• Secure with a couple of rubber bands.
• Make a shutter by taping a couple of pieces of black tape over the hole.

The pinhole camera needs to remain still when a photo is being taken, attaching it to a tripod is the way to go.

• Glue a 1/4 inch nut to the base of the film cartridge so it can be attached to a tripod. Use epoxy resin glue for a strong bond although glue from a glue gun will work.
• Add some blu-tac into the winding hole and insert a beverage tab. This will be the camera's winder.

I made shorter and longer camera bodies to test the difference this made to the field of view.

The first roll of film was shot late afternoon, no measurement of the amount of light about was taken. The photos were developed at a camera shop which still would developed 126 film. Early photos taken with exposure times of 10 - 20 seconds did not come out well, while exposure times of 45 seconds seemed to be in the zone, while 1 minute seemed too long. While the photos were not perfect, I was impressed that some shots came out at all with such old, expired film and using such a basic camera design.

Turns out with very old film, the glue attaching the lead to the film can degrade, causing problems when it's being advanced through the photo gate. Something to look out for.

The second roll of film was taken in bright sunshine. I went for exposures of about 20 seconds or so.

Much can be learnt by trial and error and recording the results. This is the basis of exposure banding where 3 photos of the same scene are taken with different exposure times. The shots above were taken in bright morning sunlight with exposure time of 5 sec, 10 secs and 15 secs. The time-of-day effect exposure times as normally, more light is about in the middle part of the day. With these 3 photos, 10 seconds looks about right, the 15 second photo being over exposed.

I purchased a few more rolls of the 126 film but as the results would be uncertain, I didn't want to spend money sending them off to be developed and scanned. In hindsight this was probably a mistake as it led me to buying a developing tank and developing chemicals as I had read it was possible to develop color film in black and white developer to get a black and white negative. The roll came out black. At first, I thought there was no images, but by holding the strip of film against a very bright electric lamp an image was able to be made out. I took a photo of it with my phone and converted into a positive image using the 'Negative Image' app. Top Tip: Get color film developed at a camera shop.

The amount of light there is when taking a photo can vary greatly and it can be difficult to judge with your eyes. So, I downloaded an app called 'Light Meter'. This shows how much light there is. The unit used to measure light is the lux, where 1 lux equals the light from a candle at 1 meter away. I am still amazed at the vast change in light depending on the circumstances. Here's some examples...

Light in lux:

Direct Sunlight 32,000 to 140,000

Ambient Daylight 10,000 to 25,000

Overcast Daylight 1000

Sunset & Sunrise 400

The vast difference in the amount of light, depending on conditions results in pinholes exposures times from a few seconds during sunny days to 15 minutes and above for indoors shots.

These large changes in lighting conditions encountered, is reflected in the f-stop aperture scale used in photography. Each stop number is twice the size of the one before it. e.g. f2 is twice the area to f2.8. A smaller number represents a larger opening.

35 mm film is the same width as 126 film and so will fit into a 126 cartridge. To do this the cartridge needs to split open. I found a broken cartridge could be glued together and that 35mm film could be fitted into the it. Fitting the film needs to be done in complete darkness. I used a photographic change bag to do so.

126 film has a backing paper on it which shows the number of each exposure though a little window. I didn't attach the backing paper to the roll of 35mm film I installed into the 126 cartridge. Instead, I taped over the little window at the back of the cartridge to prevent light getting in. So how am I to know how many shots I have taken and how much to roll the film on before taking another photo? I make a note in a notebook when a pinhole photo is taken, listing lighting conditions, subject and exposure time.

But how much should I roll the film to frame the next shot? Thats the pi problem. Turns out pi isn't really a number i.e. 3.14, its actually the ratio of the circumference of a circle to its diameter. Now, a roll of film has a diameter, and it has a circumference, but these change as you take more photos and roll more film on.

By measuring the diameter of the spool which the film will be rolled on to and measuring the diameter when all the film has been rolled on and knowing the length of each photo frame and applying pi, it is possible to calculate the arc - how much to turn the film roller to frame each photo. The math's show the amount to rotate the film roller for the same circumference-arc decreases as more film is rolled on. One turn was required at the start, while only .59 turn at the end of the roll.

The practical way of doing this calculation is to load an exposed roll of film into the cartridge, mark off each photo frame and then observe how much the film roller needs to be rotated to align each frame. Taking these observations, I came up with the following guide:

Start of roll: 1 full turn.

3-4 photos 7/8 turn

5-14 photos 3/4 turn

15-24 photos 2/3 turn

Another thing to be aware of is film is springy and will pull back after it is rotated. This can be stopped by locking down the turning knob with some blu-tac after it has been rotated.

A roll of black and white 35mm film (400 iso) was installed into a split 126 cartridge and taped together while in a photographic change bag to provide complete darkness. This pinhole camera was made using cardboard from the box the film came in.

After the photos were taken, the roll of film was removed from the pinhole camera in a change bag, placed into a developing tank and developed using a mono-developer. After it had dried, it was scanned using my phone camera and a bike light. A piece of tissue paper was used to defuse the light. I am sure there are better ways to convert the film into digital format, but I don't have that gear. The images were then converted into positive ones using an app called Negative Image.

These pinhole photos were taken in sunshine with exposures times varying between 2-15 seconds, with most being 5 seconds long. The photo of the kettle was taken inside with an exposure of 15 minutes.

A roll of Color (iso 100) 35mm film was installed into a used 126 cartridge. The film was developed at a camera shop. This pinhole camera had a 70mm long body compared to 50mm for the black and white pinhole photos. The longer body narrowed the field of view and made the images look closer, but it also made composing the photos more hit and miss. Most of these images had an exposure time of 10 seconds. The fence 5 seconds and the white sign 2 seconds.

Worldwide pinhole camera day occurs on the last Sunday of April each year. This is an opportunity to take a pinhole photo and upload it for others to see.