October 31, 2007

Build Your Own Astro Cameras!

For the monetarily-challenged astrophotographers (such as myself), there is a simple alternative. Single-use, disposable cameras can make excellent astronomical cameras; with some modifications of course.

The idea behind the whole concept is simple: even though the camera is handicapped with a focal plane of around f/10, the removal of the shutter mechanism allows for long-exposure photography. All the original pictures taken by me on this site are taken at f/2.8, and more often than not are a 30-second exposure. However, for the budget-minded astrophotographer, we are simply replacing the poor focal length with more time to collect light. A 25-minute exposure will generally, under decent conditions, provide a photo yielding about 2.5 more stars than are visible. Not too shabby, especially since disposable camera bodies are free from most photo labs. You also will want to pick up some used film canisters with toothed spindles.

Since this technique is so useful, let's go through the steps to successfully disassemble, modify, and use our new astrocamera.

  1. Open the camera body cautiously by unsnapping the plastic tabs. One plastic tab should already be removed by the original film processor. Unsnap all the pieces, four in total: the front, the back, the middle (main camera part), and a cylindrical film roll.

  2. Find out if the camera model used a flash. If it does not, skip to step 3. The flash unit retains its charge long after use and can be quite dangerous. Since we are photographing very dim stars, we do not want a flash so we need to remove the unit completely. If the camera has a flash unit, you must short out the large capacitor by connecting both leads with an insulated wire. Do this more than once!!!

  3. Now that we have either disabled the flash unit and removed it (or skipped that step entirely if you did not have one) its time to get the shutter mechanism out. You will need to remove the lens assembly temporarily so we can reach the mechanism. The lens assembly is normally on a piece of black housing and there may be a metal band securing it. Remove this C-shaped piece of metal and discard. Be careful not to get your fingers on the lens! This can ruin an image and causes the camera to be out of focus. At this point carefully remove the lens and set it somewhere safe, preferably a lens (or glasses) microfiber cloth.

  4. With the lens assembly removed you should see the shutter mechanism. It is a hinged metallic piece. Remove the spring it is connected to and the hinged metallic piece itself. Leave the plastic piece it is connected to alone.

  5. With the shutter mechanism removed, carefully replace the lens assembly.

  6. With the lens assembly replaced, snap the camera body back together.

And there we have it; a perfectly functioning astrocamera. We still need to load it with film and that can get a little sticky because a disposable camera runs reverse of what a regular camera does. Here's the steps for film loading:

  1. Remove a toothed spindle from the used film canisters you acquired.

  2. Put the toothed spindle in the reusable film canister.

  3. Attach the end of the film to the spindle with a small piece of masking or electrical tape and wind it up.

  4. Put it into the film canister with a little bit of extra film hanging out.

  5. Secure the top by screwing it in; we don't want light getting in here.

  6. Fasten the extra film hanging out to the original cylindrical canister.

  7. Put the camera body back together.

And there we have it! A perfectly functional astrophotography camera. Unless your going for star trails, you're going to have to have a device to properly track the sky.

Check out my post on barnyard trackers!!!

On a personal note, I've done this once before when I was a kid in space camp and the pictures turned out awesome! I'm running mostly on memory on what we did, but to fill in the holes, I borrowed heavily from this site at astrosociety.org.