Recently I've been playing around with some longer exposures during which I rotate the camera in a way that, if structured, would have the axis running down the center of the lens. Here is one such image, as you can see the center of the image doesn't show much blur while the outside shows the effect of the half-second exposure during the rotation.
Is there any sort of device - tripod head or otherwise - that would allow one to mount a camera and then provide some stabilization for a smooth rotation such as this? I've thought about starting to build such a device, but if someone else has solved the problem, I'm certainly willing to buy such a mounting mechanism...