AE (Auto Exposure): Combined use of AGC and iris motor control allows shooting in a broad range of lighting conditions. AGC amplifies the video signal in low light conditions; iris reduces it in high light conditions. Motor iris control can be replaced by the CCD IRIS control.
AF (Auto focus): Available in cameras equipped with motorized focus, this feature provides automatic adjustment of the focus. AF operates by varying the focus to maximize the high frequency content of the central area of the picture by reference to high luminance and strong contrast elements. In some cameras, AF can be set to High or Low sensitivity modes. AF mode is not recommended for continuous 24-hour operation. See also One-push AF, Interval AF, Zoom triggered AF.
AGC (Automatic Gain Control): Circuitry that automatically adjusts the electronic amplification of the video signal to compensate for varying levels of scene illumination.
ATW (Auto Tracking White balance): In ATW mode, white balance is continuously being adjusted according to the color temperature of the scene illumination.
Backlight compensation: Special compensation option in AE (Auto Exposure) mode. When the background is too bright and/or when the subject is too dark, backlight compensation modifies the action of Auto Exposure to make the subject appear clearer.
CCD (Charge Coupled Device): Semiconductor device made of a matrix (or lines) of individual hotosensitive elements, called pixels. The optics focus the scene onto the matrix and each pixel accumulates an electric charge proportional to the local intensity of received light and to the integration time. At read out time, all charges are transferred at the same time to an output matrix protected from light, where a sequential reading may take place while a new picture starts integrating. The output matrix size is half that of the sensitive matrix size for interlaced mode CCDs and the same size for progressive scan CCDs.
CCD IRIS: Special operating mode of the electronic shutter of a CCD camera. The shutter timing is automatically adjusted to maintain the same video output level, irrespective of the scene illumination. Can only reduce the camera sensitivity. Allows the use of a fixed iris lens under variable lighting conditions. Often combined with AGC.
C-Mount: Type of camera mount in which there is 17.526 mm clearance between the lens rear mounting surface and the camera¡¯s CCD.
Composite sync: Combination of the HD and VD in one signal. Commonly used as a synchronizing or gunlock signal in B/W systems.
DSP (Digital Signal Processing): Inside a camera, sensor signals must be processed in several steps before they can be displayed / transmitted. Typical processing steps are amplification, gamma correction, black level correction, highlight compression/clipping, edge enhancement, color processing, color balance, color correction, output signal encoding. Picture quality is highly dependent on the accuracy and the stability of these processes. In DSP technology, the sensor signal is converted to digital form after initial amplification, and all processing is achieved digitally, ensuring high quality and no drift. Output signals remain in digital form or are converted back to analog depending on the camera output mode.
Electronic shutter: CCD camera operating mode where the integration time can be shortened without any mechanical device. Used for blur reduction when capturing fast moving objects, and for camera sensitivity reduction in high levels of scene illumination.
Exwave HAD technology: Technology with a nearly gapless OCL (On-chip-lens) located over each pixel of the CCD resulting in more than twice the sensitivity and 1/50 the smear compared to Hyper HAD technology.
Focal length: Distance between the optical center of a lens and the image focal point. Fixes the magnification and the angle of view of a lens. Vari-focal and zoom lenses have a variable focal length.
Gain: The electronic amplification factor of a signal.
Gamma: Correction law introduced in the camera output signal to compensate for the non-linearity of the CRT (Cathode Ray Tube) in video monitors. A typical gamma value is 0.45, which results in the brightness component of the CRT picture appearing to be linear.
HAD (Hole Accumulated Diode): CCD technology with improved performance in spectral response, vertical smear and sensitivity. The HAD sensor also introduced a higher pixel count and electronic shuttering capability.
Horizontal Resolution: Number of equally spaced vertical black-to-white or white-to-black transitions that the camera is able to reproduce, divided by the aspect ratio (usually 4:3) to make a comparison between horizontal and vertical resolution easier. Usually expressed as TV lines per picture height. Indicates the amount of horizontal details that can be perceived. Horizontal resolution is limited by the number of pixels in one line and by the type of color filter used, if any.
Hyper HAD: A derivative of the HAD sensor that incorporates microscopic lenses mounted over each sensing pixel. Hyper HAD sensors have no perceptible smear and are nearly twice as sensitive as HAD sensors.
ICR (IR Cut Removable): This function is useful in low light environments. With the IR cut filter removed, the sensitivity of the camera to IR illumination is increased.
Iris: An adjustable sized aperture in a camera lens that controls the amount of light reaching the imager. Compensates for changing lighting conditions. Iris control may be either manual or automatic, depending on the application and the type of camera. When iris is fixed, a variable electronic shutter can be used instead (CCD Iris).
Lux (lux): The SI measurement of light intensity taken at the surface which the light source is illuminating. The measure of the total lumens falling upon a unit of area. 1 lumen per square meter. One Foot-candle equals 10.76 lux.
Minimum illumination: Minimum light level needed to achieve a 50% or 100% video output level when the camera is at maximum gain and the lens iris fully open. Can be computed from the nominal sensitivity, lens characteristics and maximum gain.
NTSC (National Television System Committee): Color video standard, used mainly in the United States and Japan. NTSC uses 525 scanning lines per picture, 30 pictures (frames) per second, each frame is made up of two sequential fields containing respectively the even and the odd lines (interlace).
PAL (Phase Alternation, Line): Color video standard pioneered in Europe but also used in many other parts of the world. PAL uses 625 scanning lines per picture, 25 pictures (frames) per second, each frame is made up of two sequential fields containing respectively the odd and the even lines (interlace).
PowerHAD: PowerHAD is further improvement of the Hyper HAD CCD technology, where the microscopic lenses focus more light onto the light sensors thus increased sensitivity and reduced smear.
Restart / Reset: Special mode in which the CCD readout cycle is stopped and restarted in synchronization with an external event. In the Stop mode, the CCD still accumulates picture information.
Sensitivity: Lens iris aperture required to provide a video output signal of standard level at a specified light input. In general, sensitivity is K measured using an 89.9% reflectance grey scale chart illuminated by a 3200¡̃ illuminance at 2000 lux (color camera) or 400 lux (B/W camera), for a video output level of 100%.
S/N (Signal to Noise Ratio): The ratio, usually expressed in dB (decibels), between the normal signal output and the noise level within an electronic signal.
Slow shutter: Shutter mode with an integration time longer than 1/50 s (PAL) or 1/60 s (NTSC). Like long-term integration, the slow shutter function increases camera sensitivity when shooting slow-moving or fixed subjects. Unlike long-term integration, continuous normal video is output in slow shutter mode by use of a built-in video memory. The output picture is compatible with normal monitors and recorders.