Originally Posted by Binastro
Thanks for that.
A nice read of things that I had forgotten.
It doesn't get into the question of what materials are used in multicoating lenses.
Also how rays at an angle are dealt with.
It also does not say how can one can judge with certainty, from visual observation, whether a surface is multicoated or not.
Also does a moisture film or haze affect the appearance or colour seen visually on a single coated or multicoated surface?
How do single coated and multicoated surfaces change in appearance when looked at at increasing angles?
A wikipedia article confirms that a single coating on high index glass can reduce the light loss to less than 1%.
Unless the article is incorrect in some fundamental way, it addresses most things that I would be curious about. Of course, that's only me, — but it is consistent with what your friend mentioned.
Specific coating materials vary between manufacturers, as well as the optical designs. The details are invariably proprietary, and as the article indicates, not all multi-coatings even have the same number of layers. At the end of the article the author does mention brightness differences between single- and multi- coated lenses, but those aren't diagnostic judgments that could be made with "certainty" IMO.
Certainty, I'm afraid, is reserved for death and taxes.