CCD Security Camera Lens Mounting
A ccd camera lens mount makes the mechanical connection between the camera body and the lens itself. Sometimes there is an electrical connection made as well. This applies only to cameras that do not have a built-in lens. You will also find lens mounts used to connect modular optical components that are used in the laboratory. Usually this is a C-mount or T-mount (discussed in detail below).
There are three types of lens mounts in use today. They are a screw-threaded type, a bayonet mount, or a friction lock. You will find most modern CCTV camera bodies that do not have a built-in lens use the C-mount screw-threaded method. This method is simple and reliable way to mount the lens, and provides for a wide variety of lens selection.
Bayonet mounts have 2 or 3 tabs at the base of the lens, which then fit into recesses in the mounting plate on the camera. The tabs can be “keyed” so that the lens is installed only one way, allowing for electrical connection between the lens and body, which is useful for SLR cameras. To install the lens with a bayonet mount, the tabs are aligned to the recesses, and then the lens is turned, and generally is locked into place with a spring-loaded pin.
Breech lock, or friction lock, uses a rotating ring and alignment pins to attach the lens to the camera. These are generally not used for ccd camera lenses. They are used mainly for movie cameras.
Screw-Mount Methods for Lens Mounting
There are three screw-mount types in common use with CCD camera lenses. They are the “C-mount,” “D-mount,” and “CS-mount.”
The chart outlines the differences:
| Mount | Frame Size | Thread Diameter | Thread Pitch | Flange Focal Distance |
| C-Mount | 16 mm | 25.4 mm (1 inch) | 32 TPI | 17.526 mm |
| CS-Mount | 16 mm | 25.4 mm | 32 TPI | 12.52 mm |
| D-Mount | 8 mm | 15.88 mm | 32 TPI | 12.29 mm |
Flange focal distance is the distance from the image sensor to the lens mount.
Frame size is the maximum image sensor format that can be accommodated by the mount. This is an important point to consider. Both C and CS mount are for the larger 16 mm image sensor size, while the D mount can only work with the smaller 8 mm sensor. The difference between C and CS mount is the flange focal distance, which affects the ability to focus the lens to the image sensor, and also affects the field of view. There’s more information in my general article about CCD camera lenses.