My new Cheez-It® camera of course!
The camera is made from 24×18″ black Coroplast, gaffers tape, black poster board and one Cheez-It® cracker. I went through the whole bag to find the one with the smoothest center hole. All the rejects were promptly eaten. The hole was 2.5mm, at this diameter the optimum focal length (from the pinhole to the photo material where the size of the pinhole will be the sharpest) was 15 feet! Well, we were going to have to see how 18″ worked.
A pinhole of 2.5mm at a focal length of 18″ gave me an aperture of f/183. I was using Ilford 8×10″ Photo Paper which sits at around ASA/ISO 6. My Sekonic light meter will actually go to f/128 so I used that to get close. A grey card reading of the scene at ISO 6, f/128 was 2 minutes. You will need to compensate for Reciprocity Failure which is a problem when exposing silver based photo materials (like film or paper) for extremely short or long times. In this case I knew that I needed about 10 times the exposure. My exposure was 20 minutes (2 minutes x 10).
You may think that an exposure of 2 minutes is quite long. Not really for a pinhole. In my studio I use 2400 watts of halogen light to light my subject. This was a problem. I knew that first of all since we’re not at the optimum focal length of the pinhole we weren’t going to be sharp. Secondly, there’s no way I would be able to hold perfectly still for 20 minutes. But I tried it anyway. I loaded the paper negative under a red safelight into the side panel I built into the camera. I kicked on the lights, sat down and pulled at the piece of tape I had covering the lens to start the exposure.
2400 watts of halogen lighting isn’t good for the eyes, so I had sunglasses on. This worked great because I could watch the clock. About a minute in the heat hit me. There was no way I could sit here for 20 whole minutes. I closed my eyes and listened to the ticking of my wall clock. Five minutes in the first bead of sweat started to form on my brow. Ten minutes in my legs (which were crossed) started to fall asleep. Fifteen minutes in I had an itch on my nose that nearly wrecked the whole shot. This was probably one of the most painful 20 minutes I’ve ever endured for a shot. Once the twenty minutes was up I covered the pinhole, turned off the lights and took a walk. My hands, arms and legs were numb.
In the darkroom the shot came out quite nice. The image here is scanned in and inverted but I’ll ideally contact print it to another sheet of photo paper and tint it orange. The color of baked cheese products.