The M42 thread is a standard for lens mounts introduced in the 1950s. It is a screw thread with a diameter of 42 mm and a pitch of 1 mm. Many camera manufacturers have used this thread, including Pentax, Praktica, Zenit, and many others.
The M42 thread is a standard for lens mounts introduced in the 1950s. It is a screw thread with a diameter of 42 mm and a pitch of 1 mm. Many camera manufacturers have used this thread, including Pentax, Praktica, Zenit, and many others.