Olympus — manual-focus OM mount telephoto zoom, 35-105mm f/3.5-4.5, push-pull design
Olympus Zuiko Auto-Zoom 35-105mm f/3.5-4.5 was a manual-focus telephoto zoom for the OM system, the compact SLR line Olympus launched with the OM-1 in 1972. It extended the OM Zuiko range into general-purpose zoom territory for bodies such as the OM-1, OM-2 and OM-10.
It uses 16 elements in 12 groups, with a one-touch push-pull ring combining zoom and focus on a single helicoid. Maximum aperture runs from f/3.5 at 35mm to f/4.5 at 105mm, closing to f/22, with close focus near 0.31m. It takes 55mm filters, measures 85mm long by 64mm across, and weighs about 470g.
Olympus later revised the formula to 14 elements in 13 groups for an autofocus-compatible version sold with the OM-707, so this manual original renders somewhat differently and is valued more for handling than outright contrast. The push-pull collar speeds framing but can rack focus if bumped.
OM mount lenses remain widely available secondhand and adapt cheaply to mirrorless bodies. Check the push-pull zoom collar for looseness or "zoom creep", confirm the aperture ring clicks positively at each stop, and inspect elements for haze given the lens's age.