"jim" wrote in message
ups.com...
The background is that I've been trying out a Canon Powershot digital
camera on a tripod with the Canon Zoombrowser software that lets the
camera be controlled from a computer via the USB.

This works well but illuminating the subject (a ragbag of documents and
old pictures) with desk lights using ordinary GLS lights gives a
visible pulsing of light which can be seen in the monitor due to the
50Hz mains frequency. [which means 2 flashes per sec or 100Hz] This
isn't ideal as it clashes with typical camera exposure speeds.

SFAIUI professional copystand lighting is expensive, so looking for a
method of obtaining a smoothed light.

One possibility would be DC lighting, but it needs to be quiite bright.

Another possibility might be flourescent lighting - but does phosphor
coating on the tube provides some lighting persistance?

Any views on feasibility of either (& how to achieve it) or any other
suggestions would be most appreciated.

TIA
Ordinary fluorescents are worse than incandescents.
Have you tried low power fluorescents? They are switched electronically at
high frequency and should avoid the problem.
John