Schneider-Kreuznach — 300mm f/5.6 plasmat lens for 8x10 view cameras, Copal 3 shutter
The Symmar-S 300mm f/5.6, also marketed at its precise 305mm focal length, is the longer end of Schneider-Kreuznach's 1961 Symmar-S range, used as a standard lens on 8x10 inch cameras and a strong telephoto option on 5x7 and 4x5.
It retains the family's six-element, four-group symmetrical plasmat layout, multi-coated, typically housed in a larger Copal 3 shutter. Its image circle of roughly 420mm at f/22 gives 8x10 users real room for movements rather than just coverage.
Its size and weight are noticeably greater than the shorter Symmar-S lenses, needing a sturdier camera and longer bellows draw; optically it follows the same pattern of soft wide-open corners sharpening progressively toward f/22.
Good 8x10-covering lenses like this hold value on the UK used market better than shorter focal lengths. Check the large Copal 3 shutter cycles correctly at all speeds, inspect for coating wear on the sizeable front element, and confirm the retaining rings are intact.