Monday, September 16, 2013

New 8x10 Pinhole

So I decided to make another pinhole camera. For this one I had contact printing in mind. That meant BIGGER NEGATIVES! So I have a box of 8x10 sheets of Kodak CSG x-ray film in the freezer that I have been cutting down to 4x5 for the Speed Graphic. Why not burn through some of that cheap stuff and have some fun along the way? I also happened to have some left over black foam core from my previous 6x12cm pinhole camera. So I went to the drawing board (literally) and sketched out some ideas. I like the curved film plane, but this time I thought I would keep a constant distance to the pinhole instead of the constant f-stop of the 6x12cm. I went and downloaded Pinhole Designer to do the calculations for me. That is a really great program and I highly recommend it to anyone interested in making a pinhole camera. I found the optimal pinhole size and it also gave me the right angle of view so that I could make the curved plane the right radius. I came up with a 115mm film distance with a 0.5mm pinhole. That makes an f/230 camera with a field of view around 109°. Here are some crappy phone digipics of the camera as it is today.
This is the back where the film sits. There are four stand-offs in the corners to make it curve upward on the ends. You can see too that I put some camera flocking material in the back since x-ray film doesn't have an anti-halation layer and the foam core is not perfectly flat black.

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Here is the same piece with a sheet of film in it.

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Here is the front of the camera. There are two stand-offs that hold the center of the film's long edges down against the back of the camera, keeping the curve 'curvy'. The other pieces on the short ends are light traps that just slide down inside of the back. They also create friction that keeps the whole thing together without rubber bands.

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And here it is going together.

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Finally, I just used a 'drain plug' style of shutter. The exposures for this f/230 camera are long enough, especially with iso 80 x-ray film, that I don't need anything mechanical or spring loaded.

 photo CameraShutter_zps519c7e04.jpg

Here is my first 'successful' 8x10 image from this camera. Obviously, I need to put something in that will keep the film centered and I also have some light leaks to deal with. But for a first image from a basically cardboard camera, it's not too bad.