Sigma 17-40mm F/1.8 Dc Art Lens - Sony E-mount

HLA (High-response Linear Actuator) Inner zoom Water- and oil-repellent coating Aperture ring (1) Aperture ring click switch (2) Aperture ring lock switch (2) AFL button (2 locations) (3) Focus Mode switch (4) Dust- and splash- resistant structure Mount Conversion Service available Support for switching between linear and non-linear focus ring settings (for L-Mount only) (5) Compatible with Sigma USB Dock UD-11 (sold separately / for L-Mount only) Every single lens undergoes Sigma’s proprietary MTF measuring system