I have a bunch of .jpg stills that I captured with my GoPro Hero 3 Black Edition (purchased in mid-2013) that are 3920 x 2160 (size varies from 1.5 to 2.0 MB).
I can't figure out how to set the camera to capture at this resolution any more. It insists on capturing at 4:3 and its highest res, wide setting captures images at 4000 x 3000 pixels.
I recall doing a firmware update a few months back. Did this remove my ability to take 16:9 stills? I miss the widescreen stills.