William Robb wrote:
----- Original Message ----- From: "Doug Franklin"
Wasn't there also something called, I think, "orthochromatic" film
that was particularly sensitive to green?
Yup, kinda. Ortho film could be handled under a red safelight. It wasn't
that it was more green or blue sensitive, it just wasn't red sensitive
at all.
Interesting. Where I first heard of it was about 1977 or so. The local
and state law enforcement types were using it to spot marijuana plots in
the local state and federal parks and forests. Apparently, according to
some newspaper articles at the time, the color of a mature marijuana
plant stood out quite obviously on ortho film when compared to the
normal flora of the Upstate South Carolina forests.
--
Thanks,
DougF (KG4LMZ)
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