Pentax's Super-Takumar 150mm f/4 — a compact M42 medium telephoto prime.
The Super-Takumar 150mm f/4 is a medium telephoto prime made by Asahi Optical for the M42 screw mount, introduced in the early 1960s. It belongs to the Super-Takumar family and served as a compact telephoto in the Pentax system, sitting between the shorter portrait lenses and the longer 200mm and 300mm options.
This is a manual-focus M42 screw-mount lens with a 150mm focal length and a maximum aperture of f/4. Focus is by hand and the aperture uses the Super-Takumar automatic diaphragm. It is an all-metal telephoto of moderate size for its reach. Optical construction details are not asserted here beyond the verified focal length and aperture.
A 150mm lens gives a useful telephoto reach for portraits, distant details and compressed landscape perspectives. At f/4 it is a relatively slow but manageable telephoto that renders cleanly when stopped down a stop. It handles well for a long lens of its day and gives the smooth out-of-focus rendering associated with the Takumar line.
Used copies are affordable and less common than the standard primes. Inspect the longer barrel for haze and fungus, which can build up in telephotos, confirm the automatic diaphragm works and blades are free of oil, and check the focus helicoid over its longer travel. An M42 adapter allows use on mirrorless bodies where the manual focus is easily managed.