lid wrote:
Robert Coe wrote:
On Mon, 01 Sep 2008 00:22:45 -0400, Cynicor
wrote:
: You never realize just how much we're all missing due to that
horrible : orange sodium light glow until you get to a dark sky site.
I took this : from Montauk NY tonight, looking north across the
eastern part of Long : Island Sound. The light in the distance
stretches from New London CT to : Providence RI. (This is a fisheye
shot turned rectilinear.)
: : http://trupin.smugmug.com/gallery/16...129_qCraD-A-LB

Sodium lamps radiate at only one wavelength (in the visible spectrum
anyway).

Not true. Even low pressure sodium lamps radiate all over the place,
they just have one wavelength dominant. But almost no place uses
them. High pressure sodium lamps radiate at all wavelengths. IF you
can see any color at all (except yellow orange!) in objects illuminated
by them
they are broad spectrum.

So if sodium really is the culprit, you could just Photoshop it out, no?

No. It would be about equally in the R and G channels. You CAN
however buy filters that remove it (low pressure sodium that is),
but the resulting colors are not accurate. I have such filters.
They are useful only for astronomy and oddball artistic effects.

Might I reiterate how much I HATE sodium lighting? When I was a kid, not
THAT long ago, I used to be able to see stars from my home. Now
everything's just a sickly orange twilight. And as you said, it's
impossible to properly color-correct for it.