Sigma's stabilised 1:1 macro with OS — rare in macro lenses — at a lower price than the Canon L equivalent.
The Sigma 105mm f/2.8 EX DG Macro OS HSM added optical stabilisation to Sigma's 105mm macro in 2011 — a significant advantage for handheld macro work. It offers true 1:1 reproduction and competes directly with the Canon EF 100mm f/2.8L Macro IS at lower cost.
Sharpness is excellent at all reproduction ratios. The HSM motor is fast and quiet for general use but hunts at macro distances where manual focus is preferred. OS provides approximately four stops of correction — genuinely useful at moderate magnifications.
Canon EF mount with 62mm filter thread. Also available in Nikon F, Sony A, and Sigma SA mounts. Internal focus maintains constant barrel length. Front element does not rotate — helpful with polarisers. Doubles as an outstanding portrait lens.
Good used availability. Check the OS mechanism for smooth, quiet operation — grinding indicates bearing wear. The Canon 100mm f/2.8L has Hybrid IS, superior at high magnification, but costs more. Superseded by the 105mm f/2.8 DG DN Art for mirrorless.