Sigma's earlier 'Bigma' — 50-500mm without OS, the original extreme-range superzoom for DSLRs.
The Sigma 50-500mm f/4-6.3 EX APO DG HSM (original non-OS version, 2006) is the 'Bigma' full-frame super-telephoto zoom for Nikon F-mount, covering 50-500mm at variable f/4-6.3 with HSM autofocus. Twenty elements in 16 groups including 4 SLD elements. Nine aperture blades. 86mm filter thread. At 1,840g. No optical stabilisation.
The optical design uses 20 elements in 16 groups (4 SLD elements). Nine aperture blades. The 86mm filter thread. At 1,840g the lens is heavy. Minimum focus distance of 1.0m (at 50mm) to 3.0m (at 500mm). HSM motor for fast, quiet AF. No OS. Variable aperture from f/4 at 50mm to f/6.3 at 500mm. Full-frame coverage.
The 50-500mm range provides the complete telephoto coverage from standard through extreme super-telephoto in a single lens: 50mm at f/4 for moderate telephoto through 500mm at f/6.3 for extreme reach. The absence of OS in the original version was addressed in the OS version (2010, 86mm→95mm filter, 1,840g→1,970g). The 'Bigma' nickname reflects the lens's large physical presence.
On the used market the Sigma 50-500mm EX APO DG HSM non-OS is affordable as a vintage super-telephoto zoom. Condition checks: HSM AF response, 86mm front element for marks, zoom ring smoothness. No OS. Heavy at 1,840g. Compatible with Nikon F-mount FX and DX bodies.