The Tamron 17-70mm f/2.8 Di III-A VC RDX is a 25.5-105mm-equivalent lens for APS-C-format Sony E-mount mirrorless cameras. The wide to the short-tele range is ideal for everyday shooting and the fast f/2.8 constant maximum aperture suits working in difficult lighting conditions and offers improved control over depth of field. Complementing this design is a series of specialized optics, including aspherical and low dispersion elements, that produce well-corrected imagery with high sharpness, clarity, and color accuracy. Also benefitting handling, an RXD stepping motor enables quick, near-silent autofocus performance along with full-time manual focus override and a minimum focusing distance of 7.5". Suiting this lens's use in inclement weather conditions, it also features a moisture-resistant construction along with a fluorine-coated front element to protect against fingerprints and smudging. Bright constant f/2.8 maximum aperture affords consistent brightness throughout the zoom range and offers improved control over the depth of field. Two LD (Low Dispersion) elements greatly reduce color fringing and chromatic aberrations throughout the zoom range in order to realize improved clarity and color accuracy. RXD (Rapid eXtra-silent stepping Drive) autofocus motor delivers impressively quiet, quick, and smooth focusing performance to suit both stills and video applications. This focusing system also offers a minimum focusing distance of just 7.5" and a 1:4.8 maximum magnification for working with close-up subjects. Full-time manual focus override is also possible, and it is compatible with Sony's Direct Manual Focus function or fine-tuned manual control. A moisture-resistant construction benefits this lens' use in inclement conditions and a fluorine coating has also been applied to the front lens element to protect against dust, dirt, and smearing.