"Gisle Hannemyr" wrote in message
...
Take a look at the spectral sensitivity diagram for Kodak's
HIE amd HSI Ingrared films:


http://www.kodak.com/global/en/profe...13/f002_0333ac
..gif

As you can see the film is a lot more sensitive at 400 nm (blue) than
it is at 720 nm (where is where near-IR starts). This means that
unless you use a filter like Wratten #89B to cut off frequencies below
720 nm, visible light will swamp the near-IR right, so it will mainly
be a visible light photograph.

True, and many of my IR Ektachromes were taken with little or no filtration
for that exact reason. The colors are more natural, and IR sources are
enhanced in a fairly subtle way. It all depends on what effect you are after
for the shot at hand obviously.

MrT.