It wouldn't be NAB without a major 4K announcement from Sony, and that's exactly what we've got here. The company introduced the Alpha A7s at its Las Vegas press event today, bringing 4K video to the popular full-frame mirrorless camera line. The "s" in the new camera's name stands for sensitivity, and to that end it supports an ISO range of 50 to 409,600. The 12.2-megapixel full-frame sensor limits downscaling with 3,840 x 2,160 (QFHD) 4K video, ultimately resulting in higher quality footage. While you can store 1080p video internally, you'll need to use an external recorder to capture 4K video, which the camera outputs with 4:2:2 color sampling via HDMI.