Re: general questions about IR

[George L Smyth <glsmyth@xxxxxxxxx>]

--- Dirk Wright <wright@xxxxxxxxxxxx> wrote:
> I was wondering about infrared reflectance and absorption of various 
> materials. I shot some EIR recently, and materials like brick, gravel, 
> and mulch recorded as not reflecting (ie, not red). If a material does 
> not reflect IR, can it be assumed that it absorbs light at that 
> frequency? Does this further mean that these materials will soak up 
> heat, or rather get hotter, than materials that reflect IR, given 
> identical solar illumination? This can have implications for housing 
> and landscaping design beyond the normal artistic effects. 

I think that you are confusing a few things.  Light is absorbed, reflected, or
refracted.  The connection of infrared with heat has nothing whatsoever to do
with the recording of this through a silver nitrate process.  Materials that
may absorb infrared radiation will not respond better or worse to our film
based upon their resultant temperature (unless it gets to the level of, say, a
soldering iron).

You may be thinking about infrared thermography, which is a means of recording
variances in heat.  However, this has nothing to do with silver-based
photography.

Cheers -

george

=====
Handmade Photographic Images
http://members.home.net/hmpi/

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