My 35mm pinhole camera

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
Front of pinhole lens
Rear 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
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
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.

4 Comments

  1. Stu
    December 2, 2009
    Reply

    Great stuff! I made a pinhole for my EOS 20D. The results were quite interesting.

    Good luck!

  2. Jonathan
    December 6, 2009
    Reply

    Grr, it’s times like this I wish I hadn’t bought 36-exposure film. I’m about halfway through this roll and don’t have any immediate ideas for photos, but I want to see the pinhole photos I’ve taken so far!

    You’d think that in this day and age, somebody would have invented something better than film…

  3. […] made pinhole lenses for my 35mm and digital SLRs out of body caps before, but it recently occurred to me I could make a zoom pinhole lens. I have […]

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