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Chap.2
Lens and Image Sensor Technology
2.1 Lens
The generation of a high quality image is decided by many factors including light source of the environment, lens,
sensor, compression engine, etc. However, for camera itself, a lens is the most fundamental component that
firstly decides if the output of the quality is good or not. In the security industry, because the use of camera differs,
especially fixed type with C/CS mount, system installers themselves have to select and purchase a lens fitting their
specific needs.
2.1.1 Focal Length
Focal length is the distance between the sensor and secondary principal point of the lens.
The shorter the focal length, the wider field of view it offers and higher level of distortion it may cause. In contrast,
the longer the focal length, the smaller viewing angle and field of object it has.
Focal Point/
Image Sensor
Focal Length
Figure 2.1 Focal length
Chap.2 Lens and Image Sensor Technology
Backward Principal Point
Forward Principal Point
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