Sigma's fast ultra-wide for APS-C mirrorless — constant f/2.8 from 15-27mm equiv in compact design.
The Sigma 10-18mm f/2.8 DC DN Contemporary was released approximately 2023 as a constant f/2.8 ultra-wide zoom for APS-C mirrorless mounts including Canon RF. Fourteen elements in 11 groups including FLD and aspherical elements. Seven aperture blades. 67mm filter thread. At 260g. 0.12m MFD. Stepping motor AF. APS-C only (DC).
Fourteen elements in 11 groups (2 FLD + 3 aspherical elements). Seven aperture blades. The 67mm filter thread. At 260g the lens is very lightweight for an f/2.8 ultra-wide zoom. Minimum focus distance of 0.12m. Stepping motor for quiet, fast AF. f/2.8 constant aperture. DC APS-C image circle (not full-frame compatible). Canon RF mount.
The DC DN designation confirms APS-C mirrorless native design: DC (Digital Compact, APS-C) + DN (Digital Neo, mirrorless). The constant f/2.8 across 10-18mm at 260g is the primary differentiator — most ultra-wide APS-C zooms are variable aperture. The 0.12m MFD at the 10mm end enables extreme close wide-angle foreground compositions.
On the used market the Sigma 10-18mm f/2.8 DC DN Contemporary is affordable as a compact APS-C ultra-wide zoom for Canon RF. Condition checks: stepping motor AF response, 67mm front element for marks. APS-C only (DC). Compatible with Canon RF APS-C bodies (R7/R10/R50); full-frame bodies apply crop.