Lytro Inc.’s products have always felt like something from the future. In its 9-year history, the startup has only shipped two cameras, both which let you refocus still images after you’ve shot them. On Thursday, Lytro announced the Immerge, a gigantic camera rig made up of hundreds of cameras, built to shoot 360-degree virtual-reality video. The first Lytro arrived in 2012 and was built for consumers. The second, which went on sale last year, was aimed at DSLR users. While both cameras wowed photography lovers with what Lytro calls “light field technology,” neither device grew into anything close to a...