ew. Angle of view is measured in degrees. Because both the focal length of the lens and size of the camera's imaging area determine the angle of view, one should not assume that two cameras with lenses of the same focal length would offer the same angle of view. A camera's arc of movement is its range. Range is measured in degrees, with 15000 degrees being on the high-end. The time that it takes a camera to move from one point to another is described as its repositioning time. Moving the camera across its full range takes 1-2 second, and some cameras move more quietly than others do. Group Systems Some cameras offer gain control or automatic gain control (AGC). AGC boosts the video signal level during low light conditions. Most cameras calculate the required gain averaging the levels in the overall image-this can cause problems in high contrast situations. AGC can also upset the levels and contrasts in an image when conference participants are wearing very bright (or white) clothing. These problems should not necessarily dissuade an organization from buying an AGC camera, but should be considered, particularly in boardroom applications. White balance is another camera feature. Various lighting conditions produce different color components. Cool-temperature lighting casts a different tint on a room than does warm-temperature lighting. White balance adjusts the RGB components that, when combined, yield white in a video signal. Auxiliary Cameras Low-end video communication systems usually offer a single camera. High-end systems typically offer more than one. In addition to the camera built into the system cabinet, high-end installations include one or more auxiliary cameras. Whereas system cameras work well to capture images of conferees seated at a table, auxiliary cameras perform better for other parts of the room. Some mount scissor- fashion on a wall while others freestand (usually on a tripod). Mobile auxiliary cameras are helpful in a large room or in cases when a speaker uses a whiteboard or lectern. They off