Olympus OM Zuiko 135mm f/3.5 is one of about half a dozen medium telephoto lenses that Olympus used to manufacture for the now defunct OM SLR platform. The 135mm prime was released in two variants - the slower f/3.5 construction and slightly faster f/2.8 option. Both lenses, while discontinued in 2002, are readily available on eBay, with good copies of f/3.5 fetching about US$55 (as of September 2007) and good quality copies of f/2.8 version going for about US$100.
The optical construction of the lens consists of 5 elements in 4 groups. The build quality of the lens is excellent, which is standard for OM type lenses - barrel is metal as are aperture ring and built-in lens hood. Focus ring is fully rubberized and broad enough to provide easy and comfortable grip. The lens has minimum focusing distance of 1.5m (4.1ft), f/22 minimum aperture and accepts 49mm screw-in type filters. The lens is pretty compact and light for a medium telephoto prime, measuring 73 x 60mm (2.9 x 2.4in) and weighing 290g (10.2oz). The inner cam of the lens extends during focusing towards closeup, so the lens is actually a few millimeters longer when focused at close range.