Several years ago I got fed up with paying $300 plus for glasses and tried Zenni optical who are based in China. I've had many pairs from them, occasionally I've had a crappy frame or two but in general, the scripts and coatings have been spot on and I've found a few frames that I've been really happy with. It's allowed me to try things like multi focals with the you-beaut oleophobic and anti reflective coatings for around $80 - something that would have cost me $400 locally. Recently, I tried one of their 'Beyond UV Blueblocker' lenses in my script as they were advertised as cutting out lots of harmful 'blue light' - sort of the next step beyond std UV coatings.
When I first put them on, I noticed a slight shift towards yellow-green which reminded me of some of the minus violet filters I have used. At one point, I was pointing my violet laser at a wall which normally has a big unfocused 'splotch' of violet light around the beam but it was gone and there was only a small white-ish dot in the middle - I thought my pointer was malfunctioning...then I looked over my glasses and the violet 'splotch' returned.......hmmmm, could these be useful for my achromatic refractors I wondered?
I've tried my blueblockers on my 6" F8 - a marginal improvement but it doesn't get rid of the electric blue glow that can accompany bright objects like Jupiter. But on my 4" F5 there is a definite improvement - particularly in the shadows which normally get filled in with a murky violet 'wash' across all the dark bits. The view became a lot more comparable to my 80mm ED. I only ever use the F5's at low power because, frankly, they're a bit crap at higher mags. For less than the price of a good minus violet filter, the blueblocker glasses are a much more useful bit of kit - perhaps not as good as a decent filter but certainly an improvement using with a fast achromat.
I assume (always dangerous) that these sort of lenses are available at most optometrists - may be worth a look next time you're getting a pair of scripts....
