35mm camera lens adapters, like the Red Rock Micro pictured on page 48, are tiny little movie theaters. They project the scenes in front of the camera, not directly onto the camera's light-sensitive CCD, but rather onto a small piece of ground glass, like a projection TV screen three-quarters of an inch across. Your video camera focuses on this screen.

Because the ground glass has a recognizable surface, simply photographing the ground glass would reveal its imperfections - you'd be able to actually see the surface of the glass. To eliminate this, 35mm adapters spin or vibrate the screen. This is why your lens adapter needs batteries.

The image is also reversed - just as it is through any lens. (Fun thing to do with the kids: Take a lens - magnifying, 35mm or other - and use it to project objects in the room onto a sheet of paper.) Some 35mm adaptors contain a prism which re-inverts the image; others expect that you'll flip it in post. (Watch for a review of the Red Rock Micro in the January 2009 issue of Videomaker.)

One thing you need to be extremely wary of when using a 35mm adapter is the focus. The depth of field can often be razor-thin, and, for this reason, just looking into the 3-inch LCD that comes with your video camera probably won't be enough; you may find that you need a full-sized monitor to view the focus. Another difficulty is that there will be no auto-focus, meaning that you need to keep constant track of where your image is and where your subject is. In the motion picture world, there's a person called the "focus puller" whose job it is to measure the distance between the lens and the subject and turn the focus ring throughout the shot. This is why blocking and rehearsal are so important, and that actors' being "on their mark" is critical. When you're using shallow depths of field, using static shots is significantly easier than videotaping a moving subject.

Finally, if you're using fast primes, you'll need to zoom the old fashioned way - with your feet - moving closer for tight shots and further back for wide ones.

Images captured with a good 35mm lens, such as an 85mm f/1.8 wide-open, are dramatically different from the same image captured with your video camera's built-in zoom. Used properly in conjunction with good lighting and careful focus, 35mm lens adaptors can revolutionize your movie making. Used in conjunction with your camera's built-in zoom, they can help you look at making video in a whole new way.

Contributing Editor Kyle Cassidy is a visual artist who writes extensively about technology.