Using the Zoom Lens

The zoom lens fitted to most TV cameras has many practical advantages, but you need to use it wisely.

Zoom lens controls

There are several different types of zoom control;

• A manual ring on the lens barrel.

• A manual crank on a panning handle, cable-connected to the lens system.

The faster you turn the crank, the faster the zoom.

• A thumb control attached to a panning handle (usually left). This operates an electrically controlled servo system. The further you push the control, the faster the zoom action. A switch may provide different zoom rates (e.g. ×2, ×4).

• A two-way rocker switch is fitted to lightweight zoom lenses. This actuates a motorized zoom; often at an adjustable speed.

• A shoot box. This is a pushbutton control box, either attached to a panning handle, or fitted into the camera head. With it, you can instantly zoom to four or five preset lens angles (adjustable), at prearranged speeds. It may also include ‘wide’ and ‘narrow’ buttons for auto-zoom, and a meter showing the lens angle in use.

Automatic zoom systems tend to be smoother than manual operation, and can be overridden when necessary.

Take Care!

Many people change the lens angle indiscriminately, to alter the shot size. It saves moving the camera! Sometimes you may have no option, but remember, the lens angle you use can have major consequences:

• Perspective. If you intercut shots taken with different lens angles, your audience’s impressions of size, distances and proportions will alter from shot to shot! This can upset the viewer’s sense of environment or visual continuity.

• Camera handling. If you are following a subject on a wide lens angle, camera movements are easy, and focusing is simple. Change to a narrower lens angle, and it becomes much harder to keep the camera steady, to frame moving subjects, and to pan smoothly. And now focusing is often quite difficult, for even slight movements can necessitate refocusing.

• Prefocusing. Take a shot with a wide lens angle, and because there is considerable depth of field, focusing is pretty arbitrary. Zoom in to a closeup … and you will often find that the subject is now out of focus! That’s because the depth of field has become shallow at the narrow angle setting, and focusing is now critical. You will have to correct focus on air! The only way to avoid this embarrassment is to prefocus the lens; viz. zoom in beforehand, focus accurately, then zoom out for the wide shot. Now, when the time comes to zoom in, focusing will be correct.

Changing the loom lens angle

As the lens angle is reduced, and the picture zooms in, the image size increases-and the area covered decreases proportionally.

Changing charecteristics

1. At its widest angle, the zoom lens handles smoothly, and has :an increased depth of field. 2. Zoomed in to its narrowest angle, these characteristics reverse, so that camera handling becomes very sensitive, and depth of field quite shallow.