> What can I shoot in the dark that moves at a constant speed
> and is really cheap?
>
(retort suppressed due to political correctness!)
> Or can anyone suggest a set up.
>
No expert here (stating the obvious!), but I think Andy described in one of his lectures photographing a turntable with a colored tape (of known width) on the edge. So, in comparison (due to the short flash duration) I guess a "guttered" computer hard disk - they have the RPM stated in the label. Maybe also a household fan. This requires some calculations, but hey! ;)
Flatbed scanner lamps move at an apparent "constant" speed, but maybe too slow for this. Some computer fans (at the processor) can be set at known speeds (via BIOS setup).
Another, perhaps more uncomfortable option, would be to put a mark on the rubber band of a car engine, although this would require more careful alignment of the camera in a limited space. To determine the running speed, a first photo at a preset camera speed (with constant light, I guess) would provide a starting point.
I have a reputation for finding the hardest way to do something, so I'm sure there will be more ingenuous solutions. ;)
**********************
