A lens for a surveillance camera is an optical device that is specifically designed to capture images or video footage for surveillance purposes. It is typically used in CCTV (Closed Circuit Television) systems, security cameras, or other surveillance setups. The lens plays a crucial role in determining the field of view, focal length, depth of field, and overall image quality of the captured footage. It helps in focusing the incoming light onto the camera's image sensor, allowing the surveillance system to monitor and record activities in specific areas with clarity and accuracy.