Cameras with a fisheye lens are used in the ISS, high-altitude balloons, rocket bodies, and other purposes. The reason is that fisheye lenses have several advantages over rectilinear lenses.
Flat-Earthers claim there is an evil intention behind the usage of fisheye lenses. In reality, the use of fisheye lenses is not unreasonable. If it is desired to have a rectilinear image output, then it is not hard to defish fisheye images to rectilinear ones..
An action camera like a GoPro® has various advantages:
- Wide field-of-view. A rectilinear SLR camera with a rectilinear wide-angle lens does not have nearly as wide a field-of-view.
- Fixed focus and a deep depth-of-field. Very close objects, far away objects, and everything in between is in focus. No focusing is needed.
- Small and lightweight.
- Cheap and disposable. Many vendors are producing action cameras. It is cheap and easy to replace one with another.
- Weatherproof, waterproof, and durable.
- Plenty of standardized mounting options that work across products from different vendors.
- Wireless control. These cameras can transmit videos over a wireless connection.
- Action camera – Wikipedia