The Focal Length is measured in mm. As a guide:
a short focal length (e.g. 2.5mm) = a wide angle of view
a long focal length (e.g. 16mm) = a narrow angle of view
Depth of Field
The Depth of View is the distance within which objects in a picture are in focus.
A large Depth of Field means almost all objects in the Field of View are in focus.
A small Depth of Field means only a small section of the Field of View are in Focus.
F Stop - is the lenses ability to gather light depending on the aperture and focal length.
CS or C Mount
The 2 standard CCTV camera lens mounts. The difference between the two is simply the distance between the lens and the CCD image sensor.
C Mount - 17.5mm
CS Mount - 12.5mm
All of our CCTV Lenses can be configured for use as CS or C Mount
Manual or Auto Iris
For changing light conditions (e.g. cameras positioned outdoors), Auto Iris lenses are needed.
For indoor use, manual iris lenses are sufficient, as light levels will not vary too much.