Hi Andy

You're idea of using a voice coil is really on the spot!!! That's exactly what I had to do for my final year project! :-))

We used a loudspeaker voice-coil to modulate pneumatic flow by using it in a flapper-nozzle assembly. It gave much faster and higher-resolution response than conventional methods, and the elasticity of the air I think absorbed any vibrations that a change may have introduced. Since we had a very small range to cover, the limited motion of the speaker wasn't a drawback. Plus it was waayyyyy cheaper than using a stepper motor :-))

However I can't think of a way to get a voice coil big and strong enough to move something as heavy as a camera. Although theoretically possible, to be feasible there'd be a lot of heating to take care of.

How about linear solenoids, how is their response? Anybody worked with them?

kundi