Archived posting to the Leica Users Group, 2008/07/02
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> FWIW I have varifocal lenses and the chart with the various choices > of lens material at my Optician has a column related to the > chromatic accuracy. The best of the optical plasics was not that > with the highest refractive index, but one in the middle. I chose it > for this reason, rightly of wrong. I do not see any fringing. Frank > > > On Jul 1, 2008, at 12:27 AM, Peter Klein wrote: > >> Optometrists or anyone who knows the subject: I just go a new pair >> of bifocals. The distance prescription seems great. But the >> reading lenses do something I've never experienced before. When >> the gave me a newspaper to check how I felt when reading, the >> contrast of the letters appeared noticeably lower my old glasses. >> Then I realized that large black letters had color fringing. I >> looked at a square picture which was mostly black, and I saw a >> reddish-amber fringe at the top, and a blue fringe at the bottom. >> Huh? >> >> The young guy fitting my glasses (a technician, not the optometrist >> who does my eye exam) first met my observation with silence. After >> I insisted several times that I was seeing the color fringes, he >> said that it might just be that I was not used to the new >> prescription, and the fringing would go away in time. But he also >> said that because I got a frame that had no bottom wire, they had >> to use polycarbonate lenses rather than the generic optical plastic >> I'd had on my previous glasses, and this has slightly less good >> optical properties. He said that they could upgrade the lenses to a >> better material for about $30. But he advised me to keep them for >> a couple of weeks first and see how I felt then. >> >> The lighting at the optometrist's was a mixture of sunlight and >> incandescent light. At home under tungsten light, I am seeing the >> same fringing on black bars or squares on white paper. The fringes >> are always horizontal lines, not vertical. The fringing doesn't >> happen without glasses, or with my old glasses. Possible >> confounding factor: It was very hot in Sunday night, and I got very >> little sleep. >> >> Has anyone else ever seen this color fringing with spectacles? Any >> advice? >> >> --Peter >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information