belloq wrote:
Indeed, the lenses appear to be greyish to me in the those photos, but certainly not reflecting amber color. However, so many shots on screen and in production photos reflect amber color. I wonder if the original amber lenses were swapped out or lost at some point during its use for promo and molding?
About a year ago in another thread the general topic of of lens color was brought up. I'm no expert but I researched it some to understand the basics of the phenomenon and the optics terminology to describe it.
A colored lens is basically a filter. An amber colored lens filters out any light frequencies not among the component color frequencies of amber. The color amber is defined as the combination of colors red and green, RGB (255, 165, 0). To see the amber color there needs to be a source of light containing equal intensities of red and green (such as a white light) on the opposite side of the lens compared to the side that we're viewing the lens from. The light passing from one side of the lens through the other side is called transmitted light. Only amber light or its component colors red and green can be transmitted through an amber lens (100% of red intensity is transmitted; 165/255=64% of green is transmitted; 0% of blue is transmitted).
Reflected light does not go through the lens but bounces back from the outer surface of the lens to the same side as the light source. The color of the reflected light is the color of the light source.
Pigments and imperfections in the lens such as scratches, fine cracks, and contaminations such as dust, haze, and even fungus which can grow within a lens can create "subsurface scattering" where we actually see the lens itself diffusely illuminated. But the color may or may not be amber depending on how it propagates along the lens and the color of the contaminants.
I took a few photos of my 1979 standard Vader mask to check lens color under different lighting conditions. These are the original amber lenses, obviously old! Lots of scratches and fine cracks within them, with some haze from a few hundred applications of Armor All over the years.
Under very bright light, the dominant color I see in these tests is a cloudy gray-ish (even green-ish) white due to subsurface scattering within the lens itself. This could be one possible explanation for the color seen in the lenses in photos of the original mask, even if the original color was amber. It may still actually be amber but can only be seen under particular lighting conditions. The best way to ascertain the lens color of the original mask is to see them from the front with only a white light source behind the lenses.