abbe normal? <ducking>
-D > On Sep 7, 2019, at 9:52 AM, Mitch Haley via Mercedes <mercedes@okiebenz.com> > wrote: > > >> On September 7, 2019 at 9:14 AM Curley McLain via Mercedes >> <mercedes@okiebenz.com> wrote: >> >> >> I go to a great ophthalmologist. They have a store in house, but don't >> make you use it. he just prints out the Rx and I can get it filled >> anywhere. I've been buying the "industrial quality eye protection" >> with titanium frames from wally land. (Safety glasses, polycarbonate) > > Polycarb is strong, has a halfway decent refractive index, blocks UV, and is > cheap. > But it likes to warp a bit in the mold and the chromatic aberrations are huge > so it's not the right stuff if you value visual accuracy. The stronger the > prescription, the worse it gets with different colors focusing differently. > Good old CR-39 plastic and crown glass have better focus, (abbe value 58-59) > but their low refractive indexes make for thick and heavy lenses. > > Trivex has a better abbe value (43), but costs more and has a lower > refractive index. > 1.66 and 1.74 high index plastics have an abbe value of 32, scarcely better > than PC's 30. > > https://www.allentownoptical.com/abbe-value-interpretation/ > > _______________________________________ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
