Re: light trap (Joe Butts)
Re: light trap (Joe Butts)
- Subject: Re: light trap (Joe Butts)
- From: "Stephen P. Clark" <email@hidden>
- Date: Tue, 31 Jul 2001 13:29:27 -0500
- Organization: at a Mac...
Joe (& Bruce),
Pardon my intrusion; a light trap - in this context - is a device that acts as a
non-light-reflecting structure to enable as "dark" a target as can be reasonably
achieved. The ColorTron used to come with a little cardboard fold-up device
for this function, to provide an absolute black calibration target when doing
the device calibrations.
Hope this helps.
SP Clark
Chicago
email@hidden wrote:
>
In a message dated 7/30/01 10:17:59 PM Pacific Daylight Time, Bruce Lindbloom
>
on the email@hidden writes:
>
>
> 7) It would also have been nice to have a light trap as one of the patches.
>
> This would be a square hole in the chart with a small box lined with felt
>
> (maybe here's where GretagMacbeth could use up their black flocking
>
> inventory!) stuck on the back of the chart. The box could be folding for
>
> storage purposes. A light trap is very helpful in measuring the bias of the
>
> camera and optics (dark current and flare). This is _very_ useful
>
> information -- it's easy to build your own light trap out of two empty sets
>
> of nesting 4 x 5 Ektachrome film boxes.
>
>
Bruce,
>
Interesting post and valid comments and suggestions for Gretag.
>
I've been a professional photographer for over 30 years and don't know what
>
you're talking about regarding this "light trap". Could you expound on that a
>
bit. Exactly what is it and what does it do?
>
Thanks,
>
Joe Butts
>
_______________________________________________
>
colorsync-users mailing list
>
email@hidden
>
http://www.lists.apple.com/mailman/listinfo/colorsync-users