Photographers can use X-ray film in normal photography by building a "camera obscura."
Like monochrome photographic film, X-ray film consists of a layer of photosensitive material with layers of silver halide crystals on either side. The crystals create a microscopic flash of energy when exposed to X-rays or light, and each flash turns the photosensitive material near it opaque, thus creating the overall negative of the image. Photographers can use X-ray film to create black-and-white photographs, but such films may not fit into modern cameras. In such a case, a photographer may have to construct a "camera obscura" device to use them.
Instructions
1. The box for a "camera obscura" must have no openings that allow in any light.
Inspect the box. Holes or depressions in the box's material may permit light into the box, and any light entering the box from an opening other than the pinhole will lighten the film evenly, obscuring the image. Cover any holes or depressions with electrical tape.
2. A pinprick will make the camera's "lens."
Stick the pin through the very center of one of the box's smaller upright sides. This hole will permit light into the box to expose the film.
3. Go into the darkroom. Place the film on the wall of the box opposite the pinhole and tape it in place. Close the box and tape its seams shut to prevent the entry of light. Tape the pinhole. The device is now ready.
4. The camera will project the image in front of the pinhole upside down onto the film.
Test the exposure of your pinhole camera. While in the darkroom, light the candle. Point the covered pinhole at the candle, then pull the tape off the hole. Leave the pinhole open for three seconds to expose the film, then re-tape it to prevent stray light from reaching the film.
5. Remove the film from the camera and develop it as a test.
Remain in the darkroom. Extinguish the candle and open the box. Remove the film and either develop it or place it in a lightproof container for later development. This is now a test exposure.
6. Inspect the test exposure. An overly small image at the center of the print means that the pinhole is too small; in such a case, reinsert the pin into the hole and wiggle it to widen the hole. A vague or very light image implies that the pinhole is too large; in that case, build a new camera with a smaller hole. Correct any defects, then use the camera to photograph any high-contrast image of light and dark.
Tags: camera obscura, X-ray film, expose film, light into, permit light