Sigma constant f/3.5 ultra-wide for Nikon (duplicate), 15mm equivalent with HSM at mid-range pricing.
The Sigma 10-20mm f/3.5 DC HSM is the faster-aperture Sigma ultra-wide for Nikon F — constant f/3.5 across the APS-C zoom range. Nikon F mount.
10-20mm focal length. f/3.5 constant aperture. DC = APS-C coverage. HSM autofocus. Nikon F mount.
The Sigma 10-20mm f/3.5 for Nikon F is the constant f/3.5 version — faster and more expensive than the f/4-5.6 (id 3279). Same optics as id 3239 (Canon EF version). Constant f/3.5 for consistent exposure in ultra-wide shooting.
On the used market the Sigma 10-20mm f/3.5 DC HSM (Nikon) is the fast ultra-wide APS-C zoom. Condition checks: constant f/3.5, HSM. Nikon F mount.