The S-mount is a standard lens mount used in various surveillance CCTV cameras and webcams. It uses a male metric M12 thread with 0.5 mm pitch on the lens and a corresponding female one the lens mount. For the lens mounts and lenses are usually attached directly to the pcb

Printed circuit board

A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...

 of the sensor, it is often called "board lens" or "M12 lens". The supported sensor formats range from the smallest 1/6-inch type to the largest 2/3-inch having an 11mm diagonal sensor. The lens mount is usually made of plastic and the lenses lack an iris control

Diaphragm (optics)

In optics, a diaphragm is a thin opaque structure with an opening at its center. The role of the diaphragm is to stop the passage of light, except for the light passing through the aperture...

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