The Zenzanon PS 135mm f/4 is a medium telephoto lens useful for portraits and close-ups, featuring a convenient 1 meter minimum focus distance. Zenzanon PS interchangeable lenses were all developed specifically for the SQ series cameras, employing computer-aided optical design and multi-coating technology. PS lenses are equipped with a shutter that opens and closes at a signal from the camera body. Shutter speeds are available from 1/500th of a second to 16 seconds. PS lenses must be mounted with the shutter cocked.