Lenses - Security camera Lenses are either fixed monofocal or varifocal with a manual iris or auto-iris. Autoiris Lenses are designed for outdoor use or any applications with variable lighting conditions. Monofocal lenses provide fixed focal lengths from super wide angle to telephoto depending on the camera format and intended application. A Vari-focal lens is designed to meet the most challenging jobs by giving the installer the flexibility to adjust between different focal lengths using only one lens. When the situation calls for an odd focal length lens or you are not sure of the correct focal length required for the installation, using a Vari-focal lens is the perfect choice.