My second pair of good but old glasses have polished edges, with which i do see reflections but it is very different from the aberrations i see with the zenni glasses. When wearing both the zenni pairs, the prescription is exact but if i look slightly to the side the colours start to seperate and get worse and worse the further i move from the centre. With the other pair i have from the UK i just get annoying "shiny-ness" from the polished edges but colour seperation is non existent. Both my lenses are several mm smaller than the zenni lenses, but i doubt that is what the main cause is. Maybe my old glasses are CR39? but they are the same thickness it seems as the zenni ones and seem pretty tough, no real scratches after 3 and a half years and i heard CR39 is pretty fragile? how true is this? Also, i am wondering if the AR coating on the zenni lenses may be the cause of the problem? I have never had an AR coating before and after having it to be honest i'm fine without it. I made up a weaker pair of glasses to help relieve eyestrain when reading and using the computer, i made it up at -6 and -6.25 so 2.5D less than my prescription. Works great but i get the same aberrations! The colour separates and there is like a red and yellow outline to things when i look off from the centre. So i am not sure. its hard to get anything with a better abbe value than polycarbonate that is also as tough as polycarbonate. I would experiment with the high index lenses but they are quite pricey for me, if they are going to turn out no good. Also what do you mean by "It could be the optical design"? I would have thought all of zennis standard lenses would be from the same manufacturer? I have thought about trivex but no discount sites offer it and to have it put into a frame will be pretty expensive and a real hassle. Also any recommendations with regards to frames that can take a lot of abuse? Thanks for your help
Mike On Apr 11, 10:28 am, Chuck Knight <[email protected]> wrote: > Actually, polycarbonate has the worst optical qualities (abbe value) of any > common material, and exhibits greater aberrations than the other options. > > Usually. > > Zenni is renowned for the quality of their optics, so I doubt it's anything > *in* the lens that is creating the problem. It could be the optical > design...different lens manufacturers can design the lens slightly > differently That may account for the problem you're having. > > OR... And, this is only a theory... It could be the polished lens edges. > > You said the other glasses didn't have the edges polished. Could your > problem be, not aberrations, but internal reflections? > > As an experiment, you could mask the edges of the lenses, and see if it > helps. Electrical or masking tape should work easily, and be easily > removable. > > -- Chuck Knight > > On Fri, Apr 10, 2009 at 4:39 PM, banana <[email protected]> wrote: > > > Hi, > > I have pretty high myopia left eye -8.75 with -1.00 astigmatism and > > right eye -8.50 with -1.00 astigmatism. > > I cannot afford to buy glasses from an optical store and usually wear > > contact lenses. I am starting to wear glasses more often now as i > > have had numerous minor eye infections thanks to my job. I also enjoy > > the freedom from cleaning contacts and all the hassle. I have ordered > > several times from zenni and have been very pleased with the > > glasses and with their customer service. However i have a big > > problem. The pairs i have ordered from them have a lot of chromatic > > aberration when i look to the side which is really really annoying. I > > have two older pairs of glasses which have very minimal aberrations, > > pretty much unnoticeable, and these glasses were cheap ones i got > > paid for by public healthcare when living in the UK. These glasses i > > believe are made of polycarbonate as they were kids glasses (im a > > smallish 20 year old, like thin face so i was still getting younger > > peoples frames i think, got the pairs when i was 16 and 18). Neither > > of these pairs have anti reflective coatings yet i get on fine with > > them. My newer pair has polished edges which look way nicer > > cosmetically but i find them annoying when wearing them as they > > reflect light. I got anti reflective coatings on the zenni frames. > > One problem i had with zenni was i couldn't really find a frame i > > liked that had lenses of the appropriate width (my usual glasses have > > 45mm width). Also i need frames that are very durable as i am a very > > active person, and am hoping to spend a great deal of time traveling > > and camping and need several good pairs of glasses that can take a lot > > of abuse (frame and lenses ideally) that won't cost me hundreds of > > dollars as i am pretty poor! I cannot figure out why my older pairs > > have no real aberrations yet the zenni ones are real bad. Would > > buying smaller lens sizes make a difference? Also i contacted > > 39dollarglasses about lens etc and i got a one word answer a week > > later (they say 24 hours for an answer) saying recommend high index. > > I personally don't care too much about lens thickness, although it > > might be nice to spend a bit more money for ONE pair of high index. > > But i heard that high index lenses have even worse aberrations and > > distortion than polycarbonate? As you can see i am pretty confused, > > so i'm looking for lens recommendations and advice on small but very > > durable frames. Something plain too! > > Sorry about the very long post! > > Thanks for your help! > > Mike --~--~---------~--~----~------------~-------~--~----~ Check us out at the oft-updated http://www.glassyeyes.com! You received this message because you are subscribed to the Google Groups "GlassyEyes" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/glassyeyes?hl=en -~----------~----~----~----~------~----~------~--~---
