I think Perkin-Elmer made several lenses like this one, which happens to be in f/8. I don't use it much, but I'm still amazed at what an achievement it was back in the day.
joe
19-Apr-2012 21:56
I used one of these in the army in "73/"74. I remembering it being f/11 wide open. Nikon mount. I had a new F2 at the time, but had to remove the meter to mount the lens as it was too large in dia. to mount with the meter on the camera. I remember the focal length was around 800mm, and the lens was very short like 3" long. I also used two super multi-coated takumar lenses,,, 500mm and 1000mm on a Pentax Spotmatic.