The lens that the camera looks thru determines the picture that you see on the monitor. Lenses come in a dizzying assortment, the differences are focal length, F stop, auto iris or not, motorized zoom or not. The focal length determines the field of view ( height and width of picture). The F stop determines how much light is allowed to pass thru the lens, this is important for low light applications. A auto iris lens has a motor that opens or closes the iris depending on the amount of ambient light. A motorized zoom lens allows for remote control of the focal length. If your having trouble selecting the right lens for you, then please visit the CCTVhelp.com forum for support