Archived posting to the Leica Users Group, 2008/06/30
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Peter, you might need some new aspherical apochromatic elements added to your eyeballs. Make sure you budget for the 6 bit coding and UV/IR filters for your headbone. Cheers, unhelpful hoppy Geoff http://www.pbase.com/hoppyman/e http://gallery.leica-users.org/v/gh/ -----Original Message----- Subject: [Leica] Chromatic aberration/fringing in spectacles? 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