So what is the big difference about c-mount versus cs-mount cameras? Many people don't realize that their are protocols to what lenses you can use on certain c-mount cameras. In the beginning modern cameras and lenses were made to format with CS mount rather than C mount. C mount lenses have a 17.52 length from the mounting position to the focal point of the lenses. On a CS mount camera you can use both cs-mount lenses and c-mount lenses, however, a C mount camera cannot do this. In fact it needs a special adapter a 5mm ring that is fitted in between the camera and the lens to achieve a focused image. The reason for this is with a cs-mount lens you cannot mount a lens close enough to the CCD chip-set to achieve a focus image. This is why CS mount cameras are preferred security cameras, they can adapt naturally. In the case of shopping, you don't have to worry much about where you need to buy a lens from. With a cs-mount camera you can fit pretty much any lens to and plug and play.