Sigma announced their new 24-105mm F4 DG (OS)* HSM | Art lens for PhotoPlus. It promises less falloff than similar competing lenses on full-frame cameras. The lens mounts can be changed by the factory if you switch cameras. But for video shooters, it doesn't hold focus through the zoom range. Sigma set pricing after this was filmed at $899. We also get a look at the 18-35mm f/1.8.