Dating acronyms cctv

The distance between the center of a lens, or its secondary principal point and the imaging sensor.Lower lengths give a greater field of view and less magnification.The number of electrons, usually described as the pixel's accumulated charge, is measured, and then converted to a digital value.

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Closing a physical iris is a much better way to protect a camera from being damaged by bright sunlight then simply using electronics to reduce the signal strength.This is a feature of security cameras that automatically adjusts the image to compensate for bright light to give more detail on the darker areas of the image.For example, use is to focus on the detail of a face of a person that has the sunlight shining from behind.Some DVRs and security cameras have alarm inputs, which can accept input from a sensor device such as a door contact or a passive infra-red motion detection which trigger the camera or DVR to take some action such as to begin recording. The size of which is controlled by the iris and is measured in F numbers.Generally, the lower the F number, the larger the aperture is and consequently more light can pass through the lens.