2.8~12mm Vari-focal Manual Iris Lens

Focal Lenght: 2.8~12.0mm Back Focal Length: 9.75~20.46mm F1.4~close Made in Korea 1/3" Format With manual iris lenses, the iris can be adjusted by turning a ring on the lens to open or close the iris, giving the user the ability to fine-tune the image. This is not convenient in environments with changing light conditions, such as in outdoor surveillance applications. Vari-focal lenses are designed to meet a range of security applications, providing the flexibility to adjust between different focal lengths with a single lens. So if you are not sure which focal-length is needed for specific areas, go with vari-focal lenses.