From: Gregory W. Blank (gblank@bellatlantic.net)
Date: 04/02/02-02:19:07 PM Z
Katharine;
I am not a scientist. Orange is my guess to be closest to opposite
UV. Yellow Green would be closer to the opposite for Blue as the Pyro stain
is closer to yellow.
My second guess would be that opposites are determined by how the
Sine wave for that particular color (frequency) matches in opposite the
color that is its true opposite.
In short the top of the blue wave equals the toe or bottom of the yellow
wave. In other words they mirror each other and if you flip them they could
be each other more or less.
Just a guess.
on 4/2/02 4:51 AM, Katharine Thayer at kthayer@pacifier.com wrote:
> FDanB@aol.com wrote: [on March 8, 2002]
>
> I've been puzzling about spectral density and hope there's someone here
> with enough knowledge about the physics and psychology of the
> electromagnetic spectrum to help me understand the things I'm puzzling
> over.
>
> Both pyro-stained negatives (the ones I've seen are light yellow-green)
> and Dan's orange colorized negatives are said to block the UV
> wavelengths that the platinum process responds to. My understanding of
> reasoning behind this is that the orange or the yellow-green is the
> complement of the UV wavelengths in question and therefore absorbs them
> rather than passing them through. Which color (orange or yellow-green)
> is closest to the exact complement of peak sensitivity? And my more
> fundamental question is, how does one determine the color complement of
> wavelengths that aren't on the color wheel? Sorry if this seems like a
> stupid question, but I'm having trouble wrapping my mind around this
> whole spectral density idea.
>
> And are the sensitizers used in platinum and gum sensitive to the same
> UV wavelengths or to different wavelengths; my further question being
> does it make sense to use the same colors for the different processes?
>
> Thanks for any "light" anyone can shed on this for me.
> Katharine Thayer
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