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Message: <blockquote data-quote="looksharp65" data-source="post: 2249519" data-attributes="member: 83771">I'm not the only one to see that tint. A minute ago I checked against a bluish grey sky, and through the Excursion it was magentaish grey.Not so while the sun shines, luckily.Concerning the color of the AR coatings: The color of the reflected light does indeed show what wavelength is not being transmitted, but lost in reflection.Should all the surfaces of all the lenses have that same reflective properties, the color tint might be quite apparent.But in good optical instruments, the total transmission of different wavelengths should be carefully calculated and customized to avoid this.Of course even the phase coating and lens materials play a role in this.It is not the material the AR coating is made of that determines the color of the rest reflection, because it's built by several layers of contrasting refractive indexes.It's rather the thickness of the respective layers that determines this.I've been told, and this is first-hand information, that (spectacle) AR coatings can be made with any reflection color, even white, but the customers are supposed to prefer green. This doesn't affect the transmission performance of a single lens.Oh, and, there's some info at Wikipedia too. It's quite OK:<a href="http://en.wikipedia.org/wiki/Antireflection_coating" target="_blank">http://en.wikipedia.org/wiki/Antireflection_coating</a>See second part, for example, and the part about multi-layer interference type.</blockquote>

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