What is a Lens Mount Thread Pitch?
A thread pitch is the measurement in millimeters of the distance between the threads of a screw. A lens mount serves as a connector between the body of a camera and a lens, and these mounts are basically of three types which are: friction-lock type, bayonet type and the screw type.
Understanding Thread Pitch
In the screw type lens mount, the thread pitch is an important aspect, which will determine the compatibility of the screw-type lens (which can be fitted). Apart from the C, D and CS mount, which are screw-type mounts, most manufacturers now prefer the bayonet-type mounts. This is because the screw-type mounts are not so sturdy and have problems with proper lens alignment.
The C, D and CS lens mounts all have a thread pitch of 32 TPI. TPI (Threads Per Inch) is a value given according to the UTS (Unified Thread Standard) and is based on measurements of fraction of an inch rather than a millimeter value. Although the measurement is called lens mount thread pitch, it is based on the pitch reciprocal and not directly the pitch parameter.