Re: Infra-Red and Model Portfolio shoots

["Sandor Mathe" <sandor.mathe@xxxxxxxx>]

> From:          Tom Campbell <tcphoto@xxxxxxxxxxxxx>
 
> With the exception of scientific/technical stuff, I use a 25A filter for
> most IR work.  So, another thing that I guess needs to be taken into
> consideration is the _visible_ light making it through.  Obviously,
> there's going to be more light passed by a red filter under warm light,
> as compared to a cool source.  So, while the statement about more IR
> with warm sources should be true in theory, my assessment is based on
> overall negative density using both visible and near-IR.  That may skew
> the issue some.
> 
> If you test this with an IR filter, let us know.  I'd love to know how
> much of the difference I've noted is the visible component and how much
> is IR-related.  If I beat you to it (not likely with all the other
> things I have to test!), I'll pass it on.

Boy does this have the potential for confusion.  I agree with what
you say but the terms sure do get ambiguous.  

If we are talking about black body radiation then the hotter(in
temperature, deg K) the light source, the bluer (colder colour) the
light.  When Tom talks about a "cool source" such as strobe he, means
colder in colour which means bluer which means higher or hotter
colour temperature (deg K.)

To further confuse the issue we have "cold light" as in enlarger
heads, which is a description of the method of generating the light
and means flourescent light which has no direct correspondence to the
colour temperature of the emmitted light (which can be very warm 
toned eg. red neon or blue, green and even ultraviolet). 

I have no idea about the infra-red output of any flourescent lights.

Sandor Mathe  -- sandor.mathe@xxxxxxxx
(905) 670-1225 x333  --  FAX (905) 670-1344
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