Olympus's pro OM super-telephoto — the Zuiko Auto-T 350mm f/2.8 ED with fast long reach.
The Olympus OM-System Zuiko Auto-T 350mm f/2.8 ED is a fast super-telephoto for the Olympus OM mount, introduced in 1983 among Olympus's professional ED lenses. The Auto-T token marks the automatic diaphragm and the ED designation indicates extra-low-dispersion glass. It was built for professional sports and wildlife photographers needing long reach with a bright aperture.
This is a manual-focus Olympus OM lens with a 350mm focal length and a maximum aperture of f/2.8, designated Auto-T with ED glass. An f/2.8 aperture at 350mm made it a large, heavy super-telephoto with a substantial front element, and the ED glass controlled chromatic aberration across the long focal length. The verifiable specifications are the 350mm focal length, the f/2.8 maximum aperture, the ED glass and the manual-focus OM mount; element count, filter arrangement and weight are omitted rather than guessed.
A 350mm f/2.8 offers strong reach with a fast aperture, pulling distant subjects close while keeping shutter speeds high and backgrounds smoothly blurred. It was intended for field sport, aviation, wildlife and other work where subjects are far away and light is not always ideal. The ED glass keeps colour fringing in check at the long focal length where it would otherwise be most visible.
This professional super-telephoto is rare and expensive, appearing infrequently on the used market. Inspect the large front element and internal glass for haze, fungus and separation, confirm the ED coatings are clean, and check the aperture blades are dry and responsive. Verify the heavy focus action, the tripod collar and any built-in filter slot. It is a specialist adaptation on mirrorless where its reach and speed are wanted, subject to its size and price.