A FEW YEARS AGO I decided to explore the microscopic menagerie living in a bit of rainwater that had collected in an open barrel. It proved to be a rich find. As the infinitesimal neighborhood of a single droplet came into focus under my microscope, I discovered many organisms I had never seen before. One in particular intrigued me. At first it looked like a cylindrical creature with a moving gut. But after a few moments I realized that I was peering at a tiny, tubular home being constructed by an even more tiny and highly industrious architect. The little worker trundled back and forth along the tube, snatching floating bits of organic refuse, which it then used to extend its domicile. I watched transfixed, all the while wishing I had some way to document this activity. Still photographs would have been wholly inadequate; the situation clearly required a video recording. But I didn't have a way to attach my camcorder to my microscope and thus was unable to share the odd antics of this aquatic charmer with others.

So you can understand why I was thrilled to receive a package from Charles Carter, a talented amateur scientist in London, Ontario, addressing just this problem. One can, of course, buy a commercial video camera and adapter specially built for this task, but these units are expensive. Besides, using a home camcorder has certain advantages. For example, it makes it easy for you to include a running commentary about your procedures and observations. And with the software and hardware now widely available, you can easily capture individual video frames on your computer for additional analyses.

Carter's invention consists of two parts: an adapter that optically links the camcorder with the microscope and a stand that holds the camcorder in place. Both pieces can be made in an afternoon for very little money.

If you lack a microscope, worry not. Microscopes often turn up where secondhand items are sold. For instance, you might scour your local thrift stores and pawnshops for a bargain. Carter found a simple monocular instrument at a garage sale for $10. I bought a research-quality binocular microscope from a friend for $100. And some brand-new microscopes are well within a typical amateur's budget. Small instruments can be purchased at many shopping malls for less than I paid. You can also consult the forum hosted by the Society for Amateur Scientists on the World Wide Web and check the on-line swap meet there for bargain equipment.

Carter's adapter couldn't be simpler. It uses a hood that screws around the lens of the camcorder to shade it from glare. Many camcorders just recess the lens in the housing for shading, but they still have threads for filters in front. So if your camcorder did not come with a separate lens hood, or if you don't want to sacrifice it for this project, you can probably find a lens hood of the proper diameter by rummaging through the junk box of your local camera shop. Alternatively, you can always buy a new one for a few dollars.

The eyepiece for most microscopes consists of two lenses situated at either end of a short metal tube. The top lens, the one you hold your eye near, is normally blocked off except for a hole at the center about the size of your pupil. This opening is too small for your camcorder to see through. The bottom lens, however, is larger and virtually unobstructed. And your camcorder will focus just fine with only this one lens in the eyepiece.

Because eyepieces sometimes need to be cleaned, the top lens is normally designed to unscrew from the tube. The other lens of the eyepiece may be attached more permanently, usually recessed slightly from the bottom end of the tube. Unscrew the top lens and discard it. You will also need to remove the outer housing that holds the eyepiece in place by unscrewing it from the main body of the microscope. Turn the eyepiece upside down and insert it into the eyepiece holder so that the lens projects above the top of the holder by about 1/4 inch (about half a centimeter). Use a few drops of Krazy Glue to hold it in place.

Set the camcorder lens hood thread side down onto a wide strip of masking tape that is positioned sticky side up on a flat surface. Then place the eyepiece holder neck down in the center of the hood, pressing it firmly against the tape. Now mix a batch of epoxy and pour it between the neck and the lens hood. Take care not to allow any epoxy to ooze onto the threads of the lens hood. After the epoxy sets, lift the assembly and remove any tape sticking to the lens hood or covering the eyepiece.

Although you could now just screw the adapter to the microscope and the video camera to the adapter, that top-heavy arrangement would be quite precarious. Moreover, some high-end microscopes have their eyepieces canted to the side for the comfort of the viewer, and these instruments would not be able to support the weight of a camcorder attached at an angle. But Carter devised a sturdy stand that helps to hold his camcorder in position yet lets it freely slide up and down as he focuses the microscope. The stand functions best when the eyepiece is vertical, but it should also work in situations where the eyepiece must remain at a slight angle.

Carter built the base of his stand from a piece of scrap 3/4-inch plywood to which he attached an adjustable closet rod. First affix the end of the closet rod to the base. Then place your microscope on the base, screw on both the adapter and your camcorder and adjust the microscope's focusing knob so that the camcorder is as low as it can go. Take care and make sure things don't topple over at this point.

To attach the camcorder to the rod, Carter cleverly exploits the threaded sleeve on the base of the unit (where a tripod would normally screw in). While holding the microscope-camera combo upright with one hand, mark a line on the outer tube of the closet rod about one inch below the tripod mount. Then cut the outer tube off at that point with a pipe cutter or hacksaw. Next, cut the inner tube of the closet rod so that when it is inserted all the way in, it sticks out about four inches. If you have a stage-focusing microscope, you can dispense entirely with the inner rod and attach the camera directly to the primary support.

Next, drill a 1/4-inch hole into the inner rod so that the camera can be secured using a long 1/4-20 bolt. Slip a washer on the bolt, push the bolt through the rod, and add another washer and two nuts. Now screw the bolt into the camcorder and tighten the nuts, one against the closet rod and the other against the camera. Fix the microscope to the plywood stand by securing it with a length of plumber's strapping across the base. Now you're ready to spy on an invisible realm. To use your new apparatus, focus the microscope until a clear image appears on your monitor and then adjust the zoom on the camcorder until the image fills the screen.

Although this system will enable you to take leisurely safaris through microscopic jungles, it may be difficult to gauge the size of your minute prey. The best way to address this problem is to measure on your monitor the dimensions of something of known size. For example, you can view the tiny, gridded dots in the large, gray A at the beginning of this article; they are spaced at intervals of 169 microns. I invite professional and amateur microscopists to share other suggestions for calibrating this instrument with the Society for Amateur Scientists by joining the discussion on the society's Web site.

For more information about projects described in this column, check the forum conducted by the Society for Amateur Scientists on the World Wide Web. You can also write the society at 5600, Post Road, #114-341, East Greenwich, RI 02818, or call 1-401-823-7800.

Images: Ian Worpole

The Society for Amateur Scientists (SAS) is a nonprofit research and educational organization dedicated to helping people enrich their lives by following their passion to take part in scientific adventures of all kinds.