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Setting Up Video Cameras

Clients often want video cameras in meeting rooms and training centers. Out of the box, however, some cameras do not produce high-quality images. AV pros can make some standard adjustments to improve quality. As with other AV devices, it's best to set up and adjust a camera in the environment where it will be used.

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BEFORE YOU BEGIN

Clients often want video cameras in meeting rooms and training centers. Out of the box, however, some cameras do not produce high-quality images. AV pros can make some standard adjustments to improve quality. As with other AV devices, it's best to set up and adjust a camera in the environment where it will be used.

ADJUSTING COLOR BALANCE

Color balancing is about the easiest thing you can do to ensure a quality image, but many people overlook it. Video cameras used in pro AV usually offer an automatic white balance circuit, which looks for bright or white objects and adjusts settings to reproduce proper colors. If there's no automatic setting, or if you'd like more control, perform a manual balancing–ideally using a flat white object, such as poster board, held in front of the camera.

1. Hold up the large piece of white paper in front of the camera at the approximate location of the person or object to be recorded (e.g. a microphone stand or lectern).

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2. Zoom in on the white paper.

3. Press the camera's white balance button to set the color reference level, which should create the best color reproduction for that room's lighting conditions.

Some cameras have preset color balance settings, which will lock the camera's white color temperature. But be careful with presets: Use them only if the lighting in a room rarely changes.

CONTROLLING MULTIPLE CAMERAS

Needless to say, if you're installing multiple fixed cameras, whether for church productions or distance learning, you don't always want to manually adjust all of them. With a properly configured camera control system, the client can adjust things like color, gain, gamma, and iris functions from a central location with the turn of a knob. A typical setup might look like this:

SETTING UP THE AUTOMATIC IRIS

The video camera's iris controls how much light enters. In most AV installs, you'll need to set up the camera's automatic iris so that it can adjust to changes in lighting and ensure people and objects don't look too dark or bright.
Many cameras have the iris adjustment modes on their body.

1. Make sure automatic gain is turned off.

2. Set the room lighting to a level at which it would typically be used with the camera.

3. With a subject in front of the camera, adjust the auto-iris setting until the picture is optimal.

4. If you have a waveform monitor or oscilloscope, connect the camera output to the measurement device. The brightness ot the subject (a person's face, for instance), should be in the 70 IRE range or about .7 volts (including sync). To verify, have the subject turn his head. The waveform should change.
If you don't have a scope, simply adjust the iris until the light level looks right on the subject. Once the setting has been locked in, zoom out.

Note: In cases of extreme contrast between subject and background (such as a speaker in front of a window), a camera's backlight adjustment can trim an auto-iris setting. When dealing with backlight, do the auto-iris setting first, and then the backlight adjustment, if still necessary.

QUICK TIP: ON GAIN When adjusting for dim lighting conditions, the initial temptation might be to increase a camera's gain setting. Keep in mind, though, that adding gain might magnify noise in the image, which could present problems if, for example, you're sending the images to a videoconferencing or other codec. If the camera has an automatic gain setting, try that first. If the image is still poor, then adjust the gain yourself.

Sources: AV Installation Handbook: Best Practices for Quality Audiovisual Systems, Second Edition, Infocomm International (www.infocom.org); Vaddio



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