Light-subtracting mirrors

[drk]

OK, fellow Optiboarders, we know that blue light coatings are really blue subtracting mirrors on the front surface causing residual brown-ish light transmission. (And, nota bene, the degree of darkness of the brownish transmitted light should be equivalent to the degree of blue reflectance--that is, not a whole heck of a lot. But such is the biggest scam to hit optical in my career.)

But get this: I have from my lab a mirror sample collection: one half has the mirror coat on a gray base, and you can see the net effect on the gray base. In a nutshell, gold and silver don't really change the perceived hues, but the red/orange causes a distinct blue shift (subtracts red) and the blue mirror subtracts blue and makes a more brown effect on the gray base (looks nice). I don't have a green mirror sample, but it was more neutral, too, IIRC.

What the real prize is, though, is that the sample collection has the same mirrors on a clear base (for whom I don't know) but it is pure mirror effect! So it can show:
a. that mirrors will darken the transmission a decent amount, alone. (Add that to people who want darkdarkdark.)
b. that mirrors will shift the color hue transmission. Hold one of those puppies up over a set of plano sunglasses and they'll get the real, live effect of what the mirror will do.

Case in point: Old DRK was fitting an acutal duck hunter with sunglasses...he chose for his patient a nice matte black, non-reflecting frame with gray polar lenses. Done? No, he showed what a brown lens would look like. On a beautiful fall Midwestern day the patient chose brown polar (well, that will look OK, I guess...seen it done before). "You probably don't want a mirror...scares off the ducks?" "No, I want a mirror--an orange mirror".

So he gets the orange mirror over a brown base lens. Guess what I noted, later, using my handy-dandy clear lens with orange mirror? It turns the perceived hue back to GRAY! I took a base lens that selectively passed a brown color and added a mirror that bounces the brown away. What a loser!

Does anyone know if there is a way out of this? I doubt it, because you can't just tint a polar lens whatever color you'd like. But say you could---what kind of tint would work? If it were a math equation:

BASE TINT X - Red/orange subtractor = Brown
Solve for "x".

BASE TINT X = Brown + Brown.

Answer = Superbrown?

[drk]

Wait! I have an awful Vogue sunglass with an almost red tint (why? Ask Claudio.) Adding the blue passing orange mirror over red shifted the lens away from red towards brown. So the answer is a pretty reddish brown.

[Uilleann]

This goes back to the old color wheel in art class, or trying to sort out color cast in the film dark room way back when in school. That orange mirror will lend a greenish visual cast when viewed from behind. Gold can do the same, but is usually less noticeable. Red shifts to blue. Green to rose. Blue to yellow. Purple to orangey/yellow. Etc. Silver is the only more or less neutral color that shouldn't change the base tint much if indeed at all.

I've never seen a mirror completely change the base tint of a lens however - even a "full" mirror, as opposed to a slightly less intense "flash" mirror. You are correct that you can use that reflex to help further adjust/refine the color cast the eye sees behind the lens, but again, something sounds sketchy that your lens is now completely gray. I'd suspect the lab actually screwed up and ran the lenses on an actual gray base instead of the brown you thought you were getting?

[drk]

Thanks for the comments! I was using sample lenses...no job ordered yet.

[Mauro.Airoldi]

These are some examples of mirrors that we produce, the base of the lens is devoid of color and the "darkening" that can be seen is due only to the bandpass effect of the mirror.We usually discourage customers from using mirrors alone without a tinted lens at least 50%.
In general there are two types of mirrors, those based on absorbent metal oxides and non-absorbent ones, in the photosol the second type.

[drk]

Beautiful!

[drk]