Fixed Lens and Varifocal Lens
Fixed lens cameras have a set field of view and cannot be manipulated to produce a wider or narrower angle. These lenses are generally found as 3.6mm, 4.3mm, 8mm, 12mm, etc. The higher the number of focal length, the more telephoto the image and the narrower the angle of view. However, this has nothing to do with the actual size of the lens itself. You can obtain a 3.6mm lens which can range in physical size from 1mm (on a micro pinhole type camera) to the size of a soda can (for much larger security type cameras).
Variable focus (or varifocal) lens cameras allow the user to modify the field of view from its widest most panoramic to the narrowest and most telephoto views that it is capable of. Some lenses provide a 3.5-8mm (widest at 3.5mm and most telephoto at 8mm)- whereas others may provide 5-50mm for a super zoom in ability.
Many are set up to interface with a variety of optional lenses. However, there are also cameras with built-in lenses that cannot be removed or replaced. The removable lens cameras are referred to as “C” or “CS” mount because those are the type/ size which are security industry standards. Many lens choices are available and the decision should be based on actual requirements for the application. For instance, if a wide field of view is required, there may be no reason to include a feature which allows a zoom to a tighter shot.
It should also be noted that not all varifocal cameras are not weatherproof and some will require a suitable enclosure for outdoor use. However, we do carry these outdoor housings, including those with built-in heater/ blower. Please check out all our security cameras here.