Building the Camera

About the only parameter that I'll be able to tweak on this rig is the focal length, so I want to make sure I have plenty of adjustment room. And, since the pinhole lets through a very small amount of light, the body of the camera needs to be light-tight, since a small leak will let in more light than the pinhole!

To solve both of these problems, I look again to the past, to the old-style accordion-bellows camera.

The camera pictured on the right is an old Kodak that used the bellows to fold up into the base of the camera, for easy portability. I could scavenge the bellows from this camera, but I have to destroy the camera, and since it belongs to my wife, I'll build my own bellows.

I'm starting out with a sheet of black tag-board, and a roll of black duct-tape. The Kodak camera has an interesting alternating fold design (the valley-creases on the top and bottom line up with the peak-creases on the sides.) but I'm

going for a simpler design. The peaks and valleys on all sides will match. This leaves me with gaps on the corners (see avi), but a bit of duct tape should go a long way toward fixing that issue.

I started with a 2" square that will serve as one end of the camera enclosure. It has a hole in the center which, on one end is the opening for the pinhole, and on the other is an opening for the CCD sensor.

Bellow are a printable pattern for the bellows I constructed, and an AVI that shows how the pieces fit together, for those interested in making their own. When using the relatively thick tag board, the key is to score the bellows folds on alternating sides to get a smooth crease.

The initial cut, on the left, scored and folded.

On the right, the two pieces are fastened together, and taped at the bottom. I found that by putting rubber bands around the assembly, I could stabilize it until I could tape the corners.

Taping the corners was a little tricky. I started out with an L-shaped piece of duct tape, then put a piece of newspaper in the corner (picture on the left). I used a magic marker to black the newsprint, then trimmed the excess.

One of those goes on the top of a corner, one on the bottom. The newsprint pieces form a non-stick corner. I then used more duct tape to seal the corners.

Without the newsprint, the corner joints would stick together, and the accordion would not be able to unfold.

After all the corners were taped, I added the final elements. I centered the pinhole over the top hole, and taped it into place. Then I took the sensor package from the webcam (previously disassembled for measurement), and attached it (held in place by friction, as the bottom hole was slightly smaller than the tube around the CCD.

The assembly is done! The next question to be answered is: does the damn thing actually work? Stay tuned.