Security camera lenses
Most of our cameras have two values at the end of their model name, e.g. 3.6 mm / 85°. These two values are directly related and mean:
- 3.6 mm — the focal length, which determines the angle of view of the captured scene.
- 85° — the angle of view the camera captures. For larger areas choose a wider angle; for monitoring a gate at 30 m, a narrower angle is more suitable.
Some cameras may be equipped with a so-called varifocal (VARIO) lens with adjustable focal length (e.g. 2.8–12 mm / 95–28°). Cameras with such a lens allow manual or motorised (remote) adjustment of the angle of view to suit your needs — this feature is also commonly known as ZOOM.
Reference table for choosing lens focal length
Use the table by determining the distance of the monitored object from the camera in metres in the second row. Move down the column to find the expected dimensions of the captured square.
Example: I need a detailed view of an entrance gate. The gate is 5 × 2 m and the camera is mounted on the house 10 m away. I find the value 10 m and move down the column. I see that the best fit is H (height) 3.6 m and W (width) 5.5 m, which best matches an 8 mm lens — about a 40° field of view.
