In article , matt
wrote:

it seems like the ideal equipment would be a long exposure camera with an
electronic or electronically controlled separate shutter . Modulate the
shutter with a 30Hz PWM signal over a long exposure , then change PWM phase
180deg (maintain the 30Hz timebase coherence) and do another exposure .

That's what these people are doing, using an electronicly-controlled
motor driving a disk with a slot in it. (Something like an LCD
electronic shutter would be too slow. A micromirror array could
probably respond fast enough, but is a lot more complicated to put
together.)

One way to do this more efficiently, doing all phases in one exposure,
would be to jitter the camera at the right frequency. Maybe spinning a
thin slanted piece of glass so that the image moves on the film plane
in a small circle. Maybe an off-center weight on the shaft of a motor
attached to the camera, using the flexibility of the telescope.

--
David M. Palmer (formerly @clark.net, @ematic.com)