6.3. Mirror Ball

On the opposite end of the scale, there is the mirror ball technique. It doesn't require you to take a loan, but the quality is very limited. It's sufficient, however, to be used in image-based lighting, and when it's done right it may also be good enough for smaller VR panoramas. In any case, it is very accessible, done quickly, and has been used in visual effects production for years.

The basic idea is this: There is a hard limit to how far you can push up the field of view in an optical lens system. Around 180 degrees is the maximum. It is physically impossible to catch the light rays from behind the camera, no matter how sophisticated the lenses are. Not so with mirrors. If you don't shoot the environment directly, but the reflection of an environment instead, the FOV is only determined by the shape of the mirror.