Video Camera Basic Definitions

Depth of Field: For a lens, the area along the line of sight in which objects are in reasonable focus. It is measured from the distance behind an object to the distance in front of the object when the viewing lens shows the object to be in focus. Depth of field increases with smaller lens aperture (higher f-numbers), shorter focal lengths, and greater distances from the lens

Aperture - In CCTV optics, the aperture is the diameter of the lens that controls the amount of light reaching the image sensor. It is shown by an f-number. For instance, a lens with an f-number of 1.2 will allow more light to reach the sensor than a lens with an f-number of 2.0 thus producing a brighter image.

Camera Format -This refers to the actual size of the image sensor. An image sensor is a device that converts a visual image to an electric signal. It is used chiefly in digital cameras and other imaging devices. It is usually an array of charged-coupled devices (CCD) or CMOS sensors such as active pixel sensors. Common formats are 1/4", 1/2", 1/3", 2/3", and 1". The size of the sensor directly affects the field of view obtained. Important note; the lens must be designed to fit the size of your sensor other wise the image will be vignette

Field of View or FOV-This refers the width, height, of diameter of the displayed image. Field of view is determined by the lens focal length, imaging sensor size, and the distance to the subject being monitored. Field of view is usually expressed in degrees horizontal and/or vertical.

Lux - A unit measuring the intensity of light. Full mood light is about 0.1 lux whereas full daylight is about 10,000 lux. Most color cameras can produce decent images during deep twilight. Most black and white cameras need about as much light as produced by a full moon. Specifications for camcorders (video cameras) often include a minimum luminance level in lux at which the camera will record a satisfactory image. A camera with good low-light capability will have a lower lux rating. Still cameras do not use such a specification, since longer exposure times can generally be used to make pictures at very low luminance levels, as opposed to the case in video cameras where a maximum exposure time is generally set by the frame rate.