Panasonic has made a strong full-frame mirrorless debut with the Lumix S1. You get a rugged, weatherproof and heavy body that handles well, and it delivers excellent image and video quality, even in low light. It beats rival models from Canon and Nikon feature-for-feature, thanks to dual high-speed card slots, 5-axis in-body stabilization, the clearest EVF on the market and 10-bit, 4K video with no crop. The biggest negative is the contrast-detect autofocus, which can’t stand up to the phase-detect systems on other models, especially for video. It’s also the most expensive 24-megapixel full-frame mirrorless camera at $2,500, and Panasonic is charging for a key firmware update on top of that.