My father was the optics expert in the family, but I learned a lot from him. I also use best grade optics for hunting and shooting and I can tell you that there is a reason Zeiss or Leica scopes and binos are $2500-$3000 dollars or more, performance...period, end of story. I have spent way more than the average person on good glass and I pray my wife don't sell my stuff for what I told her I paid for it when I am gone!!!
Glass is glass, but it is not all equal. Basically, all glass is made from silica sand. The glass in a spy satellite is chemically no different from the glass in the windows of your house. But, there are very big differences otherwise. So called optical grade glass is different in that it was fluxed and stirred constantly while kept in a molten state for a long time. This removes inclusions and impurities. The flux is a chemical that helps the impurities to "leave" it while molten. Once all the impurities are out the glass block is allowed to cool very slowly and it gets cut in to sizes to make lenses or whatever. This is half the battle to great optical glass. It takes a long time and is very expensive to do. Once cut and ground, depending on the future use it receives coatings that further enhance the performance. The best optical glass is made in Germany and comes from a company called Schott.
This is the glass used in Atomic Aquatics and other high quality masks. Germany perfected the processes for purifying the glass itself and the coatings for enhancing performance before WWII and continues to make it better. Japan runs a close second because they received information during the war when they were allies with Nazi Germany. Germany didn't share quite all the secrets to making great optical glass though and to this day while Japanese glass is for sure fantastic, it does not equal or exceed that made in Germany.
Bottom line, it is not a gimmick at all, Atomic Aquatics masks use Schott glass and since the glass is clearer you can see a little better when you look thru them. Personally, I don't care for the reflective "ARC" coating. The best you can do is get something like 99.4% light transmission thru the finest optical glass. Various coatings, such as those found on rifle scopes and binoculars enhance some of the light and make it appear "better" to the human eye, such as for low light performance. But each coating has it's price and detracts from the basic light transmission. Schott glass, like used in the masks with no coatings transfer 99.4% {minus maybe a very small amount} while other glass used in other masks may only transfer less than 90% to your eye. ARC coated masks will for sure make some colors under water appear brighter, but it's a trade off in low light conditions or in less than stellar visibility.
ARC looks good in Bonaire in the middle of the day at 20 feet...not so good in the late afternoon at 80-90 feet depth at a dive site with less visibility. On a night dive I would say forget it, this is where a Schott glass mask will shine.
All this said, the finest, most expensive, perfectly clear optical glass is negated to "zero" when your mask leaks. I love and appreciate fine optical glass, but I'd take a cheesy green tinted $20.00 junk glass mask that don't leak over any other mask no matter what it's made of on a dive.
Edit: I should add, it appears that the use of optical glass and possibly various "performance" coatings are just now starting to hit the scuba mask scene....like all matters of money, I expect to see more offerings along the lines of optical glass and light performance specific coatings in regards to dive masks....if the market is there they will latch onto it....I am surprised it has taken this long!!!! Who knows what we will see glass wise in the future????
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