Fast-Aperture Ultra-Wide Zoom. The Tamron 11-20mm f/2.8 Di III-A RXD’s zoom range and 35mm-equivalent focal length of 17-30mm make it great for a range of applications, including landscapes, architecture, and astrophotography. Its fast, constant f/2.8 aperture gives you excellent depth-of-field control and consistent brightness throughout the zoom range.

Advanced Optical Design. The ten-group/twelve-element optical formula includes one XLD element, two low-dispersion elements, and two glass-molded aspherical elements to give you high-contrast, color-accurate images across the image plane while reducing color fringing, chromatic aberrations, and distortion throughout the zoom range. Each lens element has a BBAR-G2 coating that combats ghosting, internal reflections, and flare while helping maintain sharpness and color fidelity even in strong light.

RXD Autofocus System. The 11-20mm’s RXD autofocus system tracks even the most fast-moving subjects quickly, accurately, and smoothly, making it ideal for still and video use. This lens is compatible with Sony’s Direct Manual Focus function and Eye AF on cameras with those features, and there’s also full-time manual-focus override for even greater precision.

Durable Construction. You can use this lens in inclement conditions thanks to its moisture-resistant build. The front element’s fluorine coating protects against smearing and debris.