There are four types of lenses for CCTV use: Fixed Aperture, Manual Iris, Auto Iris, and Zoom. If the area you wish to observe experiences infrequent changes in light, use a manual iris lens, which can be adjusted for light only by hand. If the area the Security Camera will be observing experiences frequent changes in light, use an auto-iris lens. These lenses adjust to light changes automatically. Auto-iris lenses come in Video or DC, and cameras generally support one format or the other. Be sure your lens matches the camera. To perform close-ups, get a zoom lens, manual and motorized zoom lenses are easily available from most retailers.