Chinon's telephoto — the Auto 135mm f/2.8 with decent speed for the mount.
Chinon Industries was a Japanese camera and lens manufacturer producing lenses for various camera systems alongside their own cameras. The Auto 135mm f/2.8 is a telephoto prime for the Pentax K bayonet mount, with auto-aperture operation and a fast f/2.8 aperture for a 135mm lens.
135mm focal length, f/2.8 maximum aperture (fast for 135mm), Pentax K bayonet mount, auto-aperture operation.
The f/2.8 maximum aperture at 135mm is one stop faster than the f/3.5 standard, providing noticeably shallower depth of field and better low-light performance. Chinon lenses are generally well-regarded for build quality and optical performance despite lacking the brand recognition of Sigma or Tokina. Compatible with all Pentax K-mount cameras including modern DSLRs.
Inspect for fungus, haze, and coating condition. Test auto-aperture mechanism — it should stop down and return to maximum reliably. Confirm K-mount engagement. Check aperture blades for oil contamination.