Sigma's earlier constant f/2.8 APS-C zoom with macro — pre-OS version without stabilisation.
The Sigma 18-50mm f/2.8 EX DC Macro is an earlier constant f/2.8 APS-C standard zoom with macro capability — predating the popular OS HSM version. The macro mode adds versatility over non-macro constant f/2.8 zooms.
Optically good — constant f/2.8 with decent sharpness. The macro mode provides close-focus capability at 20cm. EX build quality. No OS stabilisation on this version — the OS HSM version is much more practical.
Available for multiple APS-C mounts. 67mm filter thread. Approximately 445g — compact. No weather sealing. APS-C only. DC designation. EX build. Macro mode to 20cm.
Available used very cheaply. The 17-50mm f/2.8 EX DC OS HSM is dramatically better with OS. The macro close-focus is unique. Only worth considering at bargain prices where the macro mode adds appeal.