For CCTV camera and IP camera, Angle of Coverage is a feature that describes the angle range that a CCTV camera lens can image. Typically the video image circle is produced by a lens, which is big enough to cover the CCTV camera image sensor completely. It is also possible to include some vignetting toward the edge.

If the angle of coverage of the lens does not completely fill the image sensor, the image circle will be obvious, typically with strong vignetting toward the edge, and the effective angle of view will be limited to the angle of coverage.

For CCTV camera and IP cameras, the Angle of Coverage is mainly determined by the focal length of lens and the size of image sensor.

• Given the condition that the lense of a CCTV camera is the same, the bigger the image sensor is, the wider the Angle of Coverage will be; 
• Given the condition that the size of the image sensor is the same, the higher the number of focal length of the lens, the narrower the Angle of Coverage will be.

Usually, the size of of image sensor of CCTV camera is 1/3", or 1/2.5"; the focal length of lens is 2.8mm, 3.6mm, 4mm, 6mm, 8mm, 12mm.

With 1/3" of image sensor, 2.8mm focal length will mean about 90° of coverage; 4mm focal length means about 70° coverage, 6mm means about 43.3°coverage, 12mm focal length translates to about 20.6° coverage.

Note that different image resolution will also slightly affect the angle of coverage.