Sigma 170-500mm f/5-6.3 APO - Sigma SA, Canon EF, Nikon F, Sony A, Pentax K Mount

The Sigma 170-500mm f/5-6.3 APO is a long-reach telephoto zoom lens designed for nature and sports photography. As an Apochromatic (APO) lens, it uses special low-dispersion glass to minimise chromatic aberration. The lens features a rotating tripod collar and a multi-layer coating to reduce flare and ghosting. While it lacks modern image stabilisation, its reach and relatively compact size for the focal length made it a popular choice for DSLR users on a budget. Used units should be checked for 'zoom creep,' where the barrel extends under its own weight when pointed down. SDS inspects the internal glass for any signs of fungal growth, which can occur in older telephoto zooms. The tripod collar should lock firmly without slipping, and the manual focus ring should operate smoothly. We also test the aperture blades for oil or sticking, ensuring they snap shut quickly during exposure.