Chris,

I don't know the spec's for your CCD. Slower rates (in my experience) seem to impact "exposure" the slower the rate the harder to achieve a good black level. This is especially due to the infra-red sensitivety of CCD's.

It's easy to detect this effect by viewing the data, so you will be able to set your clock rate "visually". Heat absorbing glass will help if infra-red is biasing your result.

Thanks for the ref. to "optic flow" it looks interesting and i will read more. I assume your "stripes" are vertical so will you adjust the width of these stripes to accomodate inner/outer edges of "turns"?

regards,
p