360 lens / fisheye

[barneybroomer]

Lately I am experimenting with 3D models for dome movies and render them in Keyshot. At this moment I'm using Keyshot 3, and as "camera" I use half a bowl on the ground with a reflective material and put my Ortho camera above it. On the ground I have a emmisive layer that is blacked out for the camera. Rest of the model is dark. For a sky I use a bowl with a projected image on the inside. So far it works perfect, but very limited if I want to render a motion.
My question is, how difficult would it be to make a camera that got true fisheye 360? I could also but half reflective sphere in front of the cam and couple the movement of the half sphere and camera, but that is far from practical...

Like to hear!