Lens terminology

September 2006 CCTV, Surveillance & Remote Monitoring


Varifocal lenses offer the maximum flexibility for the CCTV installer as they can be adjusted to match the exact scene required by the end user. Once obtained, the view can be fixed by means of the lens locking screws.

IR corrected varifocal

Commonly known as day/night lenses. All of the features of a traditional varifocal lens are available but with the added benefits of IR correction. These lenses are manufactured with a special E.D. glass and lens coating. This combination allows the lens to deliver perfect focus under normal lighting and also under IR illumination.

Fixed focal

Fixed focal length lenses offer the CCTV installer fixed images of a scene. These lenses are an ideal solution when the views are known such as a fire exit door or an entrance foyer.

Aspherical lenses

Aspherical lenses are manufactured to allow more light through the lens for much clearer and crisper images. Because of this they are much better in low light conditions.

Zoom lenses

Zoom lenses differ from varifocals since once they have been set up by the CCTV installer, they will always stay in focus no matter how often the zoom ratio is changed. Zoom lenses give you the ability to view and get close ups of objects to highlight details or identification even when the object is some distance away. These are ideal for covert applications where your camera cannot be installed close to your target.

Mega pixel lenses

The megapixel lenses (high definition) are designed to capture the full resolution of megapixel cameras, providing a high contrast and a sharp picture.

Pinhole lenses

Pinhole lenses for security and industrial applications. The lenses are designed for the highest quality images where the viewing area is no more than a pinhole. The lenses can be used on both colour and monochrome cameras.

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