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F R E Q U E N T L Y
A S K E D
Q U E S T I O N S
Why is the resolution of a camera less than the pixels
on the sensor?
The resolution of CCTV cameras is usually defined in terms of TV lines.
In other words, the finest detail, expressed as the equivalent number of
TV lines, that could be resolved with a sensor with a given number of
pixels.This results in a resolution that is typically about 0.7 x the number
of horizontal pixels on the sensor.
How is sensitivity of a camera defined?
The sensitivity of a camera is normally defined as the amount of light
required (measured in 'lux') on a scene to produce a 50% video signal. In
order to be able to compare sensitivity of camera products, the scene
reflectance and the f-stop of the lens (usually f/1.4) need to be considered.
What is the difference between video and DC Iris control?
The Iris (or aperture) of a lens can be adjusted to ensure that the optimal
amount of light reaches the sensor. Modern cameras and lenses use a DC
signal generated by the exposure control circuitry in the camera to adjust
the size of the aperture. Some zoom lenses, and many older types of
lenses, have the control circuitry built into the lens.The video signal from
the camera is used by this circuitry to control the Iris.
P H I L I P S C C T V C A M E R A S
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