The ultimate in surveillance lenses, an amazing 120 mm to 1200 mm super zoom lens for CS-mount cameras. This mega zoom lens is 17-Inch long with a 1/4-20 mount on it's center ring for tripod mount ability. At it's widest the 10X zoom lens has a focal length of 120mm for an angle of view of about 2.5 degrees, or zoom to an amazing 1200mm for an objective view of ¼ degree horizontal. Up to 150x on a ½ inch CCD camera. The front ring adjusts the zoom, center ring adjusts iris, and back ring allows back focus adjustment. Has variable f-stop adjustment. Allows fine adjustments to back focus. Includes eyepiece to use as a telescope. As with all Marshall lenses..