The Lumix S PRO 16-35mm f/4 from Panasonic

Lumix S Pro 16-35mm F4 This wide-angle zoom lens combines top-level resolution with a lightweight, compact design. As a member of the LUMIX S PRO series, the LUMIX S PRO 16-36mm F4 meets all stringent LEICA standards. Its resolution excels through the zoom range and in every pixel of the image. Rugged Design for Intrepid Photography This lens is dust- and splash-resistant and designed for use at temperatures as low as 14 °F. It is tough enough to withstand even heavy field use.  Focus clutch mechanism AF and MF can be switched easily by sliding the focus ring forward. This allows smooth operation when you want to perform fine adjustment of the focus using MF after the AF completes focusing.  Video Support for Perfect Recording In addition to silent design, the lens offers both stunning autofocus and smooth aperture changes. This top-level performance allows you to record beautiful, ultra-sharp 4K video.  Welcome to new possibilities: the L-Mount Leica Camera, Panasonic and Sigma now offer a solution that allows ‘mix and match' of any of the three manufacturers’ APS-C and full-frame cameras with any lens from each other’s product portfolios.  S-R1635 : Construction The optimized configuration has 12 elements in 9 groups, including 3 aspherical, 1 extra-low-dispersion, and 1 ultra-high-refractive index lenses to minimize aberrations and ensure superb resolution.