Wide angle lens have many advantages for CCTV and IP video surveillance. The first advantage is wide field of view. See images above. The second advantage is quite good low-light performance. And last but not least,  wide angle lens provide good depth of field in compare with telephoto lenses.  Well known drawbacks of wide angle lens are possible geometrical distortion which appears as visible curvatures at the edges of a camera image and higher requirements for the camera resolution.

This is a reason to find a proper balance between the wide field of view and possible drawbacks of wide angle lenses.

To find a proper focal length for wide angle lens the CCTV designer needs to perform many calculations. To ease the lens selection the designer can use special 3D CCTV design software where you can clearly see all 3 paramteres: actual field of view, lens distortions and camera resolution.

Focal length is a distance between the entrance lens and the image sensor where rays of light are focused. The lens focal length and the size of camera sensor determine a CCTV camera field of view. The shorter the focal length, the wider the field of view.

In the past rotating focal length calculators made out of paper were good and simple tools for quick calculation of the field of view.

Now it is time to use comprehensive CCTV CAD /CAE software for CCTV design, like CCTV Design Tool or IP Video System Design Tool.

Apart from the focal length calculator this software has 3D engine for automatic design and visualization of all elements of video surveillance systems.

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