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Re: Yet another inaccurate article...
to properly capture IR that is thermal you have to cool the sensor to temperatures below what you are looking at. as we are looking at visible light with a solar reflectance of 5500 degrees Kelvin (which is the surface of the sun but not the interior) film is balanced for that. near IR is about 7700 AU which is just past the visible portion.
this is not thermal imaging though. there is a tendency to mix in heat with infrared. some heat can be photographed with infrared film if it is radiating at wavelengths that the film is sensitive to. but this is higher than people or plants would find comfortable.
what doesn't help is that the military have used IR (as is that part of the long wavelength spectrum) to look at images where a tank is hidden or where an aircraft used to be parked). what isn't obvious form the photographs is that these were usually taken off of a sensor that was cooled using either liquid notrogen or some coolant or an engineering device that cools by using forced air (I forgot the term for it) then photographed by regular film to have a hard copy image of the sensor.
glowing because they are alive...well you can take IR of a corpse. you're just looking at different reflectance based on what the surface reflects into the IR spectrum. photography is based mostly on reflectance except where the subject emits light. IR film doesn't capture that.
regards.
Frank Schiffel
Research Analyst III
Bureau of Health Resource Statistics
State Center for Health Statistics
920 Wildwood Drive
PO Box 570
Jefferson City Missouri 65102-0570
(573) 751-6279
FAX (573) 526-4102
visit our website at: http://www.health.state.mo.us/
>>> "kim navarre" <navarre@xxxxxxxxx> 10/23/98 3:32:22 PM >>>
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...
>In the October issue of "Studio Photography & Design," is an article
>authored by Andre Constantini, who is the National Tech. Rep. for
>Tamron/Bonica. The article, "Approaching the Infrared Throne," talks of
>hiding in an automobile trunk to load IR film. Well, OK, I suppose... But
>Constantini goes on to say that the film records heat, and that skin and
>folliage "appear to glow because they are alive and radiate heat."
>
>I thought you all would be interested to see that even pros make boo-boos.
>
>Happy shooting,
>Theo
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