The Parrot Bebops have a fixed camera also. The image is able to be electronically restructured to act as if the camera is on a gimbal. The image can "look" from side to side and nearly straight down. The camera has a 180 degree fisheye lens which sees a bunch and the hardware just uses what ever part is required to get the desired field of view. It is also electronically stabilized like the Tello. I was thinking maybe the Tello was similar and could be hacked to change the field of view. Lens doesn't look much like a fisheye though.