RE: Yet another inaccurate article...

[Theo Benson <TBenson@xxxxxxxxxxxxx>]

> I've been told this before too. So without getting too technical, how
> would
> I explain the heat/halo phenomena to my students ?-----Original
> Message-----
> From: Theo Benson <TBenson@xxxxxxxxxxxxx>
> To: 'infrared@xxxxx' <infrared@xxxxx>
> Date: Friday, October 23, 1998 1:56 PM
> Subject: Yet another inaccurate article...
> 
	[Theo Benson]  George Smythe's website explains it quite well, but
basically, IR film isn't sensitive far enough into the IR range to "see"
heat, unless something is so hot that it's already visibly glowing.  It
captures living things because they are strong reflectors of shorter
wavelength IR light from a source like the sun or a lamp.  Incidentally, it
also shows other things as glowing white, like rocks and white-painted
buildings.

	The glow comes from objects reflecting lots of IR adjacent to things
that aren't.  Since there's no "anti-halation" layer in IR film, bright
objects bleed light "halate" (glow) onto adjacent dark areas. 

	Hope that helps!

	-- Theo
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