Jonathan's blog

After I posted the other day about building a pinhole camera, I immediately ordered a body cap from eBay. Last night it arrived, and here’s how I made my pinhole camera.

Making the pinhole “lens”

Not only do pinholes have to be tiny in diameter, they should also be made through a thin material. I didn’t even attempt to make a pinhole directly in the body cap. I drilled a 10mm hole and superglued a piece of tin foil over the hole. Using a fine pin, I made a small hole.

Front of pinhole lens

Rear of pinhole lens

Uh, that’s it. Most guides I write have more steps than this, but making a pinhole “lens” for an SLR really is this easy.

What’s the f-number?

The formula for working out the f-number is pretty simple:

           focal length
f-stop = -----------------
         aperture diameter

The aperture diameter is the diameter of the pinhole, and the focal length is the distance between the film and the pinhole.

The Canon AE-1 Program has a small mark on the side to indicate the position of the film plane. The rough distance between this mark and the pinhole is 36mm. Getting a decent estimate of the pinhole is a little trickier, as I need to measure the diameter of the pinhole. The best I could come up with was to take a picture of the pinhole next to a ruler with my Fuji S9600 and a macro lens.

The pinhole

I reckon that’s approximately 0.2mm across.

          36
f-stop = ----- = 180
          0.2

So this is a pretty tiny aperture, and we are going to need long exposures to get it to make a decent picture on film.

Earlier on I pointed the camera out of my window. With the shutter set to its slowest value of 2 seconds, the meter reckoned it wanted an aperture of 8. 180 is 22 times greater than 8, so I need to make my shutter 22 times longer than 2. So we are talking 40-odd seconds for outdoor landscape photography in daylight on ISO200 film. In lower light conditions and perhaps on ISO125 film (such as my Ilford FP4) it’s easy to see that I might need to expose for 2 or 3 minutes.

Although 2 seconds is the longest my SLR can do automatically, it has a mode where the photographer can hold the shutter release for as long as necessary. Never thought I’d need a stopwatch for my photography!

My 35mm pinhole camera

The advantage of making a removable pinhole lens is that I can carry it around and easily change between lenses.

Keep an eye on my photo blog. When I’ve got this film developed I’ll scan and post the pinhole images there.

Update: I have now uploaded some of the pinhole photos.

The other day, I was suddenly taken by an urge to build a pinhole camera. I vaguely recall building one out of a shoebox at primary school that projected a dim image onto some tracing paper, but now that I have the equipment and a little experience in developing films at home, I thought it might be fun to make a pinhole camera that can work with film to make permanent images.

Medium-format sheet film is the ideal thing for such an application. While I have the stuff to develop 120 film, I don’t have any means of scanning it. So my system will be using regular 35mm film, which is more convenient for me.

This got me thinking about how to mount the film in the pinhole camera. Obviously when using small film, the camera needs to be shorter to project a smaller image. Could be fiddly to load individual frames of 35mm film into an oxo box! So I wondered about using the body of my Canon AE-1 Program, basically as a film holder.

But I wasn’t sure how easy it would be to cut a hole in the side of a cereal box and shove a camera in there without letting light in. So I considered building a pinhole camera around the body of my AE-1. Maybe I could jam a toilet roll tube into the FD mount, or something.

Then I found this much more sensible guide, Making a pinhole lens for an SLR. It describes how to make a body cap into a pinhole “lens”. It’s completely light-proof, easy to make, and causes no damage to the camera (assuming you have a second body cap).

So, I’ve ordered a body cap from eBay and I will be making it into a pinhole “lens”. I will, of course, scan and post the results on my photo blog. There will probably be some kind of review on this blog, too. Watch this space!