When shopping for surveillance cameras you will be confronted with the choice of fixed lens cameras and varifocal lens cameras. Cameras with a fixed lens have a set aperture that can’t be changed. The aperture is the space through which light enters the camera and needs to be adjusted to provide a wider or narrower view. If you have a fixed lens camera you will not be able to adjust the angle or range unless you physically move the camera itself. With varifocal lens cameras, the aperture can be adjusted quickly and easily. For example you can go from a 2.8mm lens to a 12mm lens without moving the camera. To understand the difference between a 2.8mm and 12mm angle, reference the pictures below.
A 2.8mm lens will provide a wider angle with less detail while a 12mm lens will provide a narrower, more detailed view. It can be very beneficial to get both views quickly without having to un-mount and move the camera. Varifocal lenses will allow you to get an overview of a wide angle such as a lobby, front porch or warehouse but will then also allow you to zoom in on a specific target such as a suspicious person or activity. Fixed lenses only allow you to do one or the other which is far more limiting.
Varifocal lens surveillance cameras do usually cost more upfront but can actually save you money in the long run. Fixed lens cameras may need to be re-installed to get better angles and often times more cameras need to be used to cover a certain field. These costs can add up overtime and can be avoided by starting with varifocal cameras. We also recommend using auto iris lenses which automatically adjust the opening of the iris to adapt to varying light conditions. If the camera is going to be used outdoors and at night, IR night vision can be especially beneficial. For more advice on purchasing surveillance cameras see our post on What to Look for When Purchasing a Surveillance Camera.