Homemade 35mm Pinhole

I had a real cheap Vivitar 35mm camera which is only a step up from a disposable camera; that being you can reload rolls of film. Since I wasn't planning on using it as a point-and-shoot, I have a digital for that, might as well turn it into a pinhole.

I was able to disassemble it, pop-out the old plastic lens and put in a pinhole lens made out of some brass shim. Unfortunately the shutter was spring activated at only one speed, similar to a Holga's shutter. So I removed it completely, this also required me to remove the catch on the winder. So it doesn't stop winding for each frame. This makes it a bit annoying, but not a big deal.

After my first set of example photos (see below) I redid the pinhole to make it a bit smaller. My first pinhole was 0.38mm, the second one is 0.28mm. Hopefully the smaller hole will give me sharper pictures, I just used a smaller needle to make it. The first shots look ok small, but a larger size and they are real soft.

Measuring the Pinhole with my Scanner

I used my flatbed scanner to measure the pinhole. I did this by putting the brass shim with the hole on the scanner and scanning at 1200dpi. I then loaded the scan file in Photoshop and zoomed real tight on the hole.

Using the marquee tool, I made a box across the width of the hole, be sure to measure the hole and not the reflection next to it. I found the easiest way to get a measurement is to do a copy and then paste the selected part into a new image. Key sequence: ctrl-c, ctrl-n, ctrl-v.

Photoshop will keep the same dimensions and dpi of the copied part for the new image. You can then get the width of that image from the Image Size tool, change units to mm.

Calculating Aperture

The aperture is the focal length, which is the distance from the pinhole to film plane, divided by the diameter of the pinhole.

In my case, I measured the focal length distance to be 24mm and from above measured the pinhole diameter to be 0.28mm.

So my aperture is: 24/0.28 = 85.7 but since that is impractical to use, I'll round it up and say I have a f/96 aperture; which is 5 stops from f/16, since every doubling of aperture size is two stops of light.

I can calculate the exposure times knowing the aperture. So if the meter says the exposure at f/16 should be 1/30 second, I would need to do 5 more stops of light; which works out to be 1 full second, five doubling of light. (1/30, 1/15, 1/8, 1/4, 1/2, 1)

Here's a little web app I made to help me calculate exposure times for my pinhole cameras: Pinhole Exposure Calculator

Construction Shots:

Example Photos: