>>2878685>get a 4.5mm 2.8 sigma>like looking through the convex mirror on a school bus - pic relatedI have something much, much better: Ricoh Theta S. It's about the size of a small tv remote control. On opposite sides are 190 degree fisheyes, which overlap for seamless 360 panoramas. You can shoot 360 stills or video. Built in wifi, you can trigger it remotely from your phone. Also has programmable interval shooting for timelapses, etc. In manual mode, you set white balance, shutter speed, and ISO.
