The Yashica Penta J is a 1962 to 1964 SLR with interchangeable M42 screw mount lenses. It was the first of a line of cameras that became known as the Yashica J series; its successors are the J-3, J-5 and J-P. Not to be confused with the Yashica J rangefinder.
The Yashica Penta J has a 50mm F/2 Auto Yashinon lens with an M42 screw thread. The camera has no internal exposure meter, but a clip-on meter that couples to the shutter speed dial was available at the time. Source: McKeown