CCTV lenses are an important part of the CCTV system, choosing the correct lenses is vital for all CCTV applications.
Most modern CCTV cameras including Bullet, Dome and Eyeball styles now come with either a fixed focal length lens or a varifocal lens, if you are unsure it is wise to select varifocal as this will be more forgiving during installation/commissioning of the camera.
Typical fixed focal length lenses include 2.8mm or 3.6mm both of which produce a wide angle field of view, ideal for cameras covering a smaller area, i.e. 4 X 4 meters for the 2.8mm and 6 X 6 meters for the 3.6mm.
Typical Varifocal length lenses include 4 - 9mm and 2.8 - 11/12mm. The 4 - 9 lens is simply a medium wide angle to slight telephoto lens, typically giving an horizontal field of view varying from 60 degrees to 30 degrees, the 2.8 - 11 (or 12) is more flexible and will give the camera a typical range of 80 degrees to 20 degrees. Note: all varifocal lenses are set once during commissioning and offer a lossless optical zoom function to allow more flexibility in the siting and location of the camera.
Lenses for C or CS mount cameras
Varifocal lenses as discussed above offer maximum flexibility in camera installations requiring a wide range of focal lengths. Focal length adjustments can be made with a turn of the dial, virtually eliminating the cost and inventory problems associated with improper monofocal lens selection.
Monofocal lenses as discussed above provide fixed focal lengths from super wide angle to telephoto depending on the camera format and intended application. Monofocal Fixed Iris lenses are for fixed lighting applications where cost is the most important consideration
Megapixel Lenses are designed specifically for use with CCD Cameras and video equipment for machine vision applications such as image processing, automated inspection, identification, automated gauging, guiding, positioning and other factory automations. For close-up and macro applications, the MLHX10 and Telecentric lens (TEC-55) are designed for machine vision systems with a wide range of magnification and viewing angles.
Manual Zoom Lenses provide manual adjustment of focal length, iris and focus. For use where variable angle of view is required. Main applications include inspection and robotics.
Motorized Zoom Lenses provide remote control of focal length, iris and focus through the use of a lens controller, used where variable focal length and remote control are required. Applications include long distance surveillance in parking lots, highways, etc.
Pinhole specialty lenses were engineered for the most covert of applications. Where discrete or covert work is needed, Computar offers a range of pinhole lenses 2.5mm up to 9mm (2/3" C-Mount type). The tapered lens tip requires only an 1/8" hole through a wall or ceiling surface.