Carl Zeiss Jena's compact Exakta tele — the three-element Triotar 135mm f/4 medium telephoto.
The Carl Zeiss Jena Triotar 135mm f/4 is a compact medium-telephoto prime from Jena, offered in the Exakta bayonet as an affordable long option in the system. The Triotar name marks a simple three-element triplet-derived design, which kept the lens light and inexpensive relative to the Sonnar teles. It served Exakta users who wanted extra reach without the bulk or cost of the faster telephotos.
This is a manual-focus Exakta-mount lens with a 135mm focal length and a maximum aperture of f/4. It is built on a Triotar design, a three-element air-spaced formula related to the classic triplet. The aperture is set on the barrel and coupled through the Exakta internal lever on supporting bodies. Filter thread, weight and other figures are omitted here where they cannot be confirmed for the specific Exakta build.
The Triotar 135mm is a modest, easy-to-carry telephoto whose simple design gives pleasant central sharpness stopped down and a soft, gentle rendering wide open. It suits head-and-shoulders portraits, travel detail shots and general long-lens work where a small light 135mm is more convenient than a heavier fast tele. Its character is soft and classical rather than clinically sharp.
Used Exakta Triotars are among the more affordable Zeiss Jena teles and turn up fairly regularly. Check the glass for haze, fungus and separation, and confirm the aperture blades are dry and the ring clicks. Inspect coatings for scratches and test the long focus helicoid for smooth travel through its full range. On mirrorless via an Exakta adapter it is a light, inexpensive vintage 135mm.