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Path: utzoo!watmath!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.auto
Subject: Re: Re: Color of the lights
Message-ID: <251@watcgl.UUCP>
Date: Sun, 28-Oct-84 16:57:31 EST
Article-I.D.: watcgl.251
Posted: Sun Oct 28 16:57:31 1984
Date-Received: Mon, 29-Oct-84 02:18:48 EST
References: <372@houxb.UUCP> <55200111@trsvax.UUCP>, <9611@watmath.UUCP>
Organization: U of Waterloo, Ontario
Lines: 11

A small nit in Kevin's explanation:  Blue light actually gives the
finest detail in any sort of optical system, since its wavelength
is shortest and diffraction effects extend shorter distances.

The reason fog lights are yellow is simply because blue light scatters
the worst of all colours, again because of its short wavelength.
If you filter out the blue, the ratio of light coming back from objects
to light scattered by the fog goes up, giving you better vision.
Filtering out the green too, leaving only red, would give even better
contrast but your eye isn't too sensitive to red so it's better to
leave the green in.