SV: oops... (was Re: Nology)

[Roland Johansson]

First it didn't show up in my mind but when thinking of this
idea a drawback appeared to me. All the welding helmets I been
looking thruu (two) are having a big green filter, looks like
that might be a problem. But why not have a LCD showing the
plate number and turning it off when a flash appear?
Hm, have to go to my fathers house and make a close examination
of his helmet in the evening



Roland Johansson
Scirocco 1,6l TIC -82
> >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/