Varifocal lens:
is a type of manual zoom lens with a small zoom ratio (ranging between 4mm to 12mm depending on brand). It is used when the focal length of the lens needs to be fine tuned to meet the requirements of the actual scene.

Video head:
is an internal part of a VCR which rotates very rapidly and writes the video signal on to the video tape during recording while reading the video signal from the tape during playback.

Vertical resolution:
is the number of horizontal lines which can be resolved in a picture. It is limited by the television scanning method - NTSC, PAL etc.

Vertical shift register:
is a part of the interline transfer CCD chip and is placed in between every column of pixels. At the end of each frame the charge from the pixels are sent to the vertical shift register (VSR) and then row by row to the horizontal shift register.

Vertical streaking:
is a type of picture distortion that occurs due to overloading of the pixels in an interline transfer chip. It appears as vertical streaks above and below the bright part of the picture.

VHS Victor Home System:
is a type of popular recording format used in video cassette recorders. The other type of formats are betamax, 8mm, system 2000 and U-matix (professional).

Vibration sensor:
is a type of device which can be activated by vibrations in a pre determined zone and can be interfaced with a switcher to switch the nominated camera for extended viewing.

Video amplifier:
is a type of amplifier used to boost the strength of a video signal.

Video cassette recorder:
is a device which can record (or playback) video and audio signals on a magnetic tape housed in a cassette.

Video distribution amplifier:
is a type of amplifier used not only to boost the strength but also create multiple outputs of the video signal.

Video intercom:
is a door entry system which uses both audio and video to communicate and/or control movement of people.

Video monitoring:
is a new trend which uses video to monitor remote sites in any part of the world. The video images are transmitted through the telephone network.

Video motion detector:
is a device which can detect unwanted movement in the picture and then generate an alarm.

Video or direct drive:

With auto iris lenses it is necessary to control the operation of the iris to maintain perfect picture levels. Video driven lenses contain amplifier circuitry to convert the video signal from the camera into iris motor control. With direct drive lenses, the camera must contain the amplifier circuitry, and the lens now only contains the galvanometric iris motor making it less expensive. The deciding factor depends on the auto iris output of the camera. Most now have both types.