Tokina's fast APS-C ultra-wide zoom — constant f/2.8 from 16.5-24mm equivalent, a landscape favourite.
The Tokina AT-X 11-16mm f/2.8 Pro DX was released in 2008 as an APS-C constant f/2.8 ultra-wide zoom — the first affordable constant f/2.8 ultra-wide for APS-C cameras. At 560g and 77mm filter thread it reflects the 13-element formula. Available in Canon EF-S and Nikon F (DX) mounts. DX/APS-C designation confirms APS-C-only image circle: 16.5-24mm full-frame equivalent range.
The optical design uses 13 elements in 11 groups. Nine aperture blades. The 77mm filter thread. At 560g the lens is moderate. Minimum focus distance of 0.3m. No optical stabilisation. Constant f/2.8 aperture. APS-C (DX) image circle — vignettes on full-frame. Available in Canon EF and Nikon F (APS-C) mounts.
The AT-X 11-16mm Pro DX was the benchmark affordable APS-C constant f/2.8 ultra-wide at launch: constant f/2.8 enables indoor event photography and low-light ultra-wide work that variable aperture ultra-wides at f/4-5.6 cannot. At 16.5-24mm equivalent, the 11mm provides extreme wide environmental coverage for interiors, venues, and astrophotography on APS-C bodies. The lens built a strong reputation for sharpness-per-price-ratio.
On the used market the Tokina AT-X 11-16mm f/2.8 Pro DX is affordable as a vintage APS-C ultra-wide. Condition checks: AF engagement (Canon EF-S or Nikon F body motor), 77mm front element for marks, and zoom ring smoothness. Confirm the Canon EF or Nikon F version. APS-C only — full-frame vignetting if mounted on FX/FF bodies.