Sigma 100-200mm f/4.5 Zoom - Unknown Mount

This manual focus telephoto zoom lens offers a modest constant maximum aperture of f/4.5 throughout its range. It features a one-touch pump action design for simultaneous zooming and focusing, making it a functional choice for portraiture and general outdoor photography on vintage film SLR bodies. The optical construction is straightforward, prioritising a compact form factor for its era. When assessing a used example, check the smoothness of the zoom/focus action, as these one-touch mechanisms can become loose or 'creep' over time. Internal dust is common in pump-action lenses, so the elements are inspected for significant debris. SDS technicians also check for oil on the aperture blades and ensure the mechanical linkage operates correctly across the focal range.