I used a hole-punch tool to make a 1/4 inch diameter hole in the lid of the tin. I then used fine sandpaper inside the box, so that flat-black spray paint would adhere to the surfaces. This reduces unwanted reflections. The pinhole was then centered in the 1/4 inch hole, and secured with tape.
The light through a pinhole will create a cone of approximately 120º. For the Altoids tin, this results in an image circle that is similar to an old silver dollar. Upon exposure, the image will have a spectacular vignette. This is exactly the way the image appears on the photographic paper, in negative. For a shutter, I used a flat magnetic business card.
One challenge with homemade cameras is the lack of a viewfinder. A little imagination, and the ability to visually ray-trace the desired scene will get you close to the desired composition. And a little luck... You will also have to guess exposures. There are many calculators available on the web. From the Ilford photo site, check out this exposure calculator. This exceptional site, by David Balihar, has excellent information about pinhole camera photography.
Pintoid Camera
With my tiny camera loaded with Ilford photographic paper, I set off to work. For about a decade, I walked from Union Station to various workplaces along Michigan Avenue. Since I use pinhole cameras frequently, I am usually able to guess exposures. The actual exposure times are not extremely critical, as film and paper usually have sufficient exposure latitude for small, or even moderate errors. Poor results can often be salvaged with the excellent scanners and software available.
This is the Merchandise Mart. I set the little Altoids camera on the wall along Wacker Drive, and simply lined up the face of the box with the building. I guessed an exposure of five seconds. Once I got home, I processed the little paper negative.
Merchandise Mart
Click for larger view
This has long been a favorite image.
