The Tamron C-Mount 4 to 12mm Varifocal Manual Iris Lens is a varifocal lens which features a 4 to 12mm adjustable focal length. Compatible with cameras using a 1/2" imager size and C-mount, the lens is designed to deliver high-quality imagery. With an aperture range of f/1.4 to close, the lens allows for clear images even in lowlight conditions. The lens surface is multicoated for reducing ghosting and flare in backlit conditions and eliminates constructional problems such as lopsided blur and focal point image degradation. The integrated slip-mount mechanism allows you to fine-tune the position after mounting the camera to set the auto-iris meter to a proper position around the lens. With the lock for each control ring (zoom and focus), you can avoid setting displacement after installation.