Streets wrote:
The lens was the standard lens that came with the Asahi Pentax Spotmatic cameras which were made until 1976. It was the last of the M42 screw mount Pentax cameras that were superseded by the K series. It is still a favorite among many of today's photographers. Many adapters are available for just about all of the name brand digital cameras in use today. There are many fine lenses by Asahi, Zeiss, etc. that are M42 mounts and are available at low prices.
Thanks for the info, Streets! Very good to know about the lenses. My husband used to shoot with a screw mount Pentax and still has the camera.