oops... (was Re: Nology)

[Tom Parker]

Ronald T. Webb <rwebb at ptialaska.net> wrote:

>I like your idea of an LCD screen similar to the expensive welding hoods. The
>opaquing action would not have to outrun the light, only go dark before the
>camera lens had collected sufficient light. Anybody know the shutter speed
>used?

There are two sources of light used to expose the film. First is the flash
from the speed camera, the second is the ambient light hanging around. The
shutter speed is likely to be around 1/125 to 1/250 of a second, certainly no
faster than 1/500. Camera flahes have very short durations. I don't know how
quickly the light builds up from the flash, but any trigger circuit would need
to detect the flash building up and get the LCD opaque before enough light had
arived.

The effect of the ambient light would be interesting, since this light is
always there, and the flash is triggered somewhere in the middle of the
exposure. The shutter opens fully, then the flash fires, and the shutter
closes. Depending on the power of the flash and the distance from the camera
to the car, ambient light would probably have no real effect on the image.

--
Tom Parker - tparker at nznet.gen.nz
           - http://www.geocities.com/MotorCity/Track/8381/