In a camera, the lens ensures that light coming from a given point in a scene reaches a given pixel. When an ideal lens is in perfect focus, light coming from a given point in the image will reach a given pixel only. This is an important optical component which enables cameras, including 3D time-of-flight (ToF) cameras, to work. 3D ToF cameras have certain distinct characteristics which have special requirements to be met with while selecting or designing the lenses. This document explains how to decide the specifications for 3D ToF cameras. It also describes how to choose or design lens holders.