Making pinhole cameras and developing negatives.

September 18th, 2012

Not a bus sign update although I am still working on that one. This was a total tangent and I am not even sure where it came from but I started making my own camera and developing the negatives myself. I have started simply with a pinhole camera and black and white 120 roll film. I wanted to use a medium format film so I can get big negatives then eventually make my own prints from them. With a large negative you can make what’s called contact prints without the use of an enlarger.

I am getting ahead of myself there though. First the camera. The simplest camera you can build is a pinhole camera so, in the words of William Shatner, it started there. The first I made from foam board, glue and tape. The pin hole was made using thin shim brass (0.06mm thick) and a very thin beading needle. I simply gripped the needle in a hemostat and pushed though the very tip of the needle. I was aiming for a hole of about 0.3mm. I checked it using my microscope and peering through it. I mounted it on some black card with black tape.

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Knowing the optimum size for the pinhole involves some maths. Any pinhole will probably produce images but there is an optimal size depending on various parameters. There is a ton of information on the Internet explaining all this and a useful calculator on the Mr Pinhole site which is the one I used.

I then made a very simple box to contain the film spools. 120 roll film comes on spools and with a backing paper behind the film itself. In the end of the spools is a slot so I made a simple spindle form little bits of brass modelling tube I have and a wooden knob to turn it. The back of the camera has a small red window to allow you to read the frame numbers on the back of the film as you wind it on. I settled on a frame size of 6cm x 6cm. There are different numbers in different positions on the back of the film depending on which frame size you use.

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The back is held in place with rubber bands. On the front I made a simple sliding cardboard shutter.

IMG_0439_1_1 First camera ready to use.

That completed the camera. I shot off a few rolls of film and played about with different exposures times. On a bright day this camera needs around a 1 second exposure. In darker conditions you lengthen this. Given the dimensions of this camera (0.3mm pinhole, 50mm focal length, 60mm frame) the aperture works out to be about 170.

Once I had taken some (boring) test shots I needed to see if I had anything. To do this I needed to develop the film. Now this I have done before. I can remember doing it when I was very young in scouts then again once at school (although that was just printing) then again some years ago when I took a little photography course in the evenings at tech. Since these times stand out in my memory I knew it was something I would enjoy hence investing the time and money into this project when I already have about 101 other things I should be doing!

I bought myself a developing tank and a changing bag. The film is wound onto a spool that then goes into the tank which is light tight but with a lid that allows you to pour in the necessary chemicals to process the film. The film needs to be put onto the spool in total darkness hence the need for the change bag. This is a heavy, double layered bag that’s totally light tight. You throw everything into it then insert your arms into elastic edged holes (now I know how a vet feels) and remove the film from the camera, remove the backing paper and thread it onto the spool. Apparently this can be tricky but I haven’t had any issues so far. I think the brand of tank makes a big difference. I am using an AP brand one.

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Tank, bag and chemicals.

You also need the chemicals – developer, stop and fixer. The film is processed in each for a certain time at a certain temperature so a thermometer is necessary as well as a water bath to maintain an even temperature. A stopwatch is also needed to time everything. The developing is the critical part. You have to pour it into the tank at a specific concentration, at a specific temperature for an exact amount of time AND agitate it with a particular rhythm to get the film to develop correctly. Normally the film will say how to develop it in a specific developer or you can look it up on the massive development chart for your particular developer and film.

If your film and your developer aren’t on it you need to experiment. Mine weren’t – I am still experimenting.

The first few films I did were very underdeveloped. I finally managed to get something looking like a picture though. The problem then is it’s a negative! You need to convert it to a positive. I found I can do some simply with my old scanner. It does a good enough job just laying the film on the bed so I can see what I have. I am still experimenting so things aren’t very good so far but I am improving.

roll1-2a-i-s Scanned negatives.

Given that I was getting something at all I decided to build a better camera. I saw a new, old, Mamiya RB67 Pro-S 220 roll film back on TradeMe and grabbed it (well, no one else bid) thinking to use it as the base of a new, more robust camera. 220 film is like 120 film with no backing paper (so you get more shots). The spools and negatives are the same as 120 though. I knew I could probably put my 120 film into the 220 back. Mamiya don’t recommend it but hunting about on the Internet it seems the mechanisms in the backs are the same except for the frame counter. All that will happen is I’ll run out after 10 or so shots while the counter indicates there are more frames available. I can live with that.

IMG_0506_1 IMG_0505_1 Mamiya RB67 back.

The back was new and unused but old. The seals in it were all shot (common and expected) but I was able to order a kit online from Jon Goodman in the states. His name is all over the camera forums as the chap to deal with and that he is excellent to deal with. I emailed him and got an almost immediate reply. I ordered a kit from Jon and payed via PayPal. Total cost was $14NZ including postage. The kit arrived today and contained new foam, instruction and a little bamboo stick to use as a tool.

IMG_0523_1 Jon’s camera foam kit.

The kit arrived today and I was able to fit it without too much trouble. Jon and his kits are highly recommended. You can email him at and mention camera foam seals in the subject.

This camera I wanted to be more sturdy than simple foam and also I wanted it to have a decent shutter. I was finding the paper one on my first camera to be tricky to use. To get a shutter mechanism I went to the local camera shops on Queen Street and got some processed disposable cameras. These are the single use ones you still see around (amazingly). When the process them they rip them open to remove the film and the battery for the flash and the rest gets thrown away. They contain lenses, shutters, plastic gears, spools and the flash electronics (useful for many things those). They’ll usually give them to you for free if you ask. I popped in and got given six of them!

IMG_0501_1 Disposable cameras.

It is a bit hit an miss what you get. I got three Kodak cameras which were perfect as I could use the shutter mechanism by itself and the lens was easy to remove to be replaced with a pinhole.

I made the body of the camera from thin plywood. It clips to the camera back using small aluminium plates. I use a piece of black felt between the two to make it light tight. The shutter mechanism bolts to the front of the camera box and I am using a cable release to trip the shutter. I glued scraps of plastic cut from the disposable camera bodies to extent the plastic arm that triggers the shutter. The photo below shows the details but the camera isn’t finally assembled yet.

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The shutter release cable uses a weird tapered thread but you can usually find a suitable nut that engages enough of the thread to make it usable. The nut is soldered to a brass strip that sits over the top of the shutter housing. A flat wooden plate closes it all off on the front to make it light tight. I arranged the bottom aluminium clip so that it pushes on the interlock on the camera back dark slide to allow that to be inserted and removed (the slide blocks off the backs so they can be removed from a normal camera without exposing the film).

IMG_0517_1 IMG_0521_1 Second camera construction.

I made two tripod mounts using suitable nuts found in my junk box and attached them to the base and the side of the camera.

I still need to varnish the outside of the box and paint the insides matt black. And I will make a shutter button that can be used in place of the release cable if necessary. It will take days to varnish as you need days between coats and I want about 4 coats. But once that’s done I can reassemble the camera and test it out.

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2 Responses to “Making pinhole cameras and developing negatives.”

  1. Eddie Says:

    “The back of the camera has a small red window to allow you to read the frame numbers on the back of the film as you wind it on.”

    – What material do you for the red window? Is it some kind of special red gel used for photography – just some something red and transparent?

  2. Simon Says:

    I used lighting gel. If you’re in Auckland you can get it form Surplustronics:

    Any theatrical lighting type place should have it. You only need a tiny bit of course.