Sigma's vintage budget standard zoom — basic 28-84mm from the Zoom III consumer range.
The Sigma Zoom III 28-84mm f/3.5-4.5 is a budget consumer standard zoom from Sigma's Zoom III range — basic 28-84mm coverage predating the EX and Art lines by decades. The most basic Sigma specification of its era.
Optically very basic — acceptable centre sharpness at best. Variable f/3.5-4.5. The Zoom III designation was Sigma's consumer tier — below the EX professional line. Adequate for casual photography of the 1990s.
Available for multiple mounts. Lightweight. Full-frame coverage. The Zoom III was Sigma's most affordable range. No weather sealing. Basic construction.
Essentially free used. Any modern zoom dramatically outperforms it. The Zoom III designation is long obsolete. Only useful at throwaway prices. A piece of Sigma's history before the Art-line transformation.