Below is a guide we’ve created for the sole purpose of educating you on the various terms that go along with CCTV or security camera lenses.

Focal Length (mm)

The focal length (measured in “mm”) of a lens determines how far the camera can see. The smaller the focal length, the wider the field of view.

Field of View (FOV)

Field of View is the area, in width, that the lens will allow you to see.If you hear the term “wide angle” then it will have a smaller lens, like 2.8mm.

Monofocal vs. Varifocal

Monofocal lenses or “fixed” lenses can only focus at a specific distance… “mono” –> one –> one length! They will have one focal length, like 16mm or 3.6mm. Varifocal lenses will usually have a range, like 2.5-6mm or 5-50mm.

Zoom Lenses

Zoom CCTV lenses are bit more expensive because, well, they’re better. They can automatically adjust focus to increase the definition on a given object.

Manual vs. Auto Iris

A manual or “fixed” iris lens is one you’d use if you are in an area where the lighting does not change, like an office. An auto iris lens will automatically adjust for light variations.

Camera/Image format

Here, we’re referring to the CCD image sensor of the camera. You’ll notice that most CCTV cameras list either 2/3”, 1/2”, 1/3”, or 1/4” for their CCD image sensor. This will affect your field of view. The larger the image sensor, the larger the field of view the camera has. For example, 2/3” will see more than a 1/3” image sensor will. Now, all of the above just applies to the camera, not the lens.

C or CS Mount

When mounting a lens to a CCTV security camera, you’ll have C or CS mount to choose from.