Video Magic on the
Rostrum and Tabletop

by Jim Stinson

Handy tips to make photos and
collections come alive on video

Capturing small, stationary objects on video may seem ho-hum, until you remember that the digital medium has entirely changed hobbyist video. With a DV camcorder and digital post, some amazing stunts are possible. You can generate dancing photos or spaceships zooming past a rasterized moon. And if you don't really care about the gee-whiz stuff, you can still create exciting video slideshows from old photos or document your matchbook collection for all those folks who just can't wait to see it.

Let's take a look at how the use of rostrums and tabletops accomplish these video techniques

What's a Rostrum?

"Rostrum" is a British term for a copy stand that lets you move the artwork, the camera or both, while capturing flat art subjects in real time. "Tabletop" videography is just what it sounds like: capturing small, dimensional subjects placed on a table for convenience. Undertaking a rostrum or tabletop project involves building your "studio," choosing your subjects and employing special lighting and shooting techniques to capture them. Figures 1 and 2 illustrate how to set up your rig, while the sidebar Rostrum and Tabletop Projects offers several subjects to spark your imagination. That leaves us free to focus mainly on procedures and lighting and lensing tricks.

Classical miniature shooting setups are still useful, but we're going to focus on setups that use seamless chromakey backings, so that you can composite your subjects onto any background you like.

Lighting Techniques

If you don't have the budget for professional light kit you can still get good results from some simple affordable substitutes. Halogen work lights from the local hardware and some large sheets of white foam core from a craft or office supply store, may be all you need to get the job done.

For a soft effect, aim the halogen work lights away from the table and bounce their light off large sheets of white foamcore (remember: the bigger the light source, the softer the light).

For just a hint of classic key/fill lighting, position your fill light and foamcore twice as far away as the key light. But remember that pronounced shadows may degrade or even ruin your compositing attempts. A cool addition is a directional spotlight placed low, beside the rear backing, and aimed forward. The goal here is to miss the chromakey background and rim light the subject. As a general rule, keep key and fill lights fairly high so that any shadows thrown by dimensional subjects are short.

The only trick to rostrum lighting is to use two lights. Each is placed on one side of the subject, at an equal distance and at a 45-degree angle to the art. If you use a glass cover platen, slight lighting adjustments will usually dispose of unwanted reflections.

Finally, light your setup as brightly as possible. Close lens distances mean very shallow depth of field in some cases as little as half an inch. The brighter your lighting, the greater the f-stop and the greater the range of focus.

The Perfect Focus

Now that lighting and object placement are to your satisfaction, let's examine camcorder techniques.

The biggest problems you'll encounter probably involve focus, framing and movement. In addition to lighting for depth of field, you'll want to freeze your focus and check it minutely before shooting.

To do this, work with a good external monitor, 13 inches or bigger, so that you can really study your subject. To lock focus, you can usually set your camcorder to auto, let it find the focus, then reset to manual. If you have true manual focus, there's no substitute for twiddling the ring while eyeballing your monitor. With large subjects like posters, it's possible to lose focus as you pan and tilt, so watch for this problem and re-shoot the scene if necessary.

Focus is also a function of lens focal length, with wide-angle lenses offering the deepest depth of field (at any given distance) and telephoto lenses the shallowest. Wide-angle lenses have two other advantages as well. First, by exaggerating apparent depth, they can add punch to small 3D objects. And, as we'll see in a moment, they make it easier to make smooth pans and tilts.

On the other hand, telephoto lenses let you keep back from the subject and out of its light. Their shallow depth of field can actually work to your advantage by throwing background textures or imperfections out of focus. Finally, telephoto start positions give you more scope for zooming in and out. You'll probably arrive at a trial-by-error compromise between the two extremes far enough away to stay clear of your lights, but close enough to move smoothly.

Be sure to use manual focus and achieve an adequate depth of field with iris and shutter settings to keep the subject in focus when panning or tilting.

Smooth Moves

What's all this about moves? Panning and tilting the camcorder brings objects on and off screen and reveals successive details in tight closeup. The problem is that these moves are minuscule compared to shooting full-size action, and consumer tripod heads are not ideal for making tiny camera shifts. The broader the move, the smoother it's likely to be. And the wider the lens, the bigger the move to get from point A to B. Unless your tripod costs over $1,000, you'll get smoother moves at wide angle lens settings.

So, that's the gist of it. Try dusting off your copy rig and bringing it into the digital age. You'll be amazed at the professional effects you'll pull off.