Having just bought a new pair of prescription glasses, I was wondering if polycarbonate is good enough for eye wear, not not lenses. Its lot lighter. Just wondering ...
they use it for many camcorder lenses (or at least they used to). But your eyes only need one piece of glass, a lens has many elements. maybe it's not good to have 12 plastic lenses in a row.
I have glasses in both polycarbonate and glass. The glass is quite a bit clearer and it doesn't easily scratch. The optical clarity is noticeable. Polycarbonate has a higher index of refraction, so lenses can be made much thinner. My prescription is pretty weak, otherwise glass would be impractical.
But if I could not have a camera lens made out of glass, I'd rather have acrylic as it has better optical clarity and doesn't scratch as easily as polycarbonate.
Different materials have various optical properties of refraction and dispersion, etc. You can obtain the specs from the supplier. There are thinner, lighter alternatives to CR-39. You need to take into consideration the overall lens design in choosing the materials.
JameelH wrote:
Having just bought a new pair of prescription glasses, I was wondering if polycarbonate is good enough for eye wear, not not lenses. Its lot lighter. Just wondering ...
It's what the new 70-200 2.8IS and 24-70 2.5IS are going to be made out of.
JameelH wrote:
Having just bought a new pair of prescription glasses, I was wondering if polycarbonate is good enough for eye wear, not not lenses. Its lot lighter. Just wondering ...
They do...Canon has been using aspherical polycarbonate lens elements for a long time (at least since the early 90's) [Canon Camera Museum]
BTW as I have chainge a lot of time prescripstion lens due to age changes I can definately can confirm that polycarbonate lens its completely rubbish if you compare with the zeiss Carat AdvantageŽ Gold that I use now ... I can see the difference in clarity/sharpness and confortness in driving.
dvarnav wrote:
BTW as I have chainge a lot of time prescripstion lens due to age changes I can definately can confirm that polycarbonate lens its completely rubbish if you compare with the zeiss Carat AdvantageŽ Gold that I use now ... I can see the difference in clarity/sharpness and confortness in driving.
The Zeiss Carat advantage is a coating it can be applied to Polycarbonate as well.
Yeah, but only for the cheapest kit lenses that are going to be used by old aunt Peggy a couple of times every year at thanksgiving and christmas only to be dropped off for prints at walmart, who'd do more to damage image quality than taking a mallet to the camera itself... omarlyn wrote:
They do...Canon has been using aspherical polycarbonate lens elements for a long time (at least since the early 90's) [Canon Camera Museum]
Manfred W. fEU wrote:
The Zeiss Carat advantage is a coating it can be applied to Polycarbonate as well.
It can applied but it has not the same resistance in years. For my specs in 2 years coated polycarbonate just has left the 70% of the coating scatered all over the lens which means poor visibility comparing with the same zeiss in glass. I was one of the biggest supporter of polycarbonate lens for eye and this is definately changed during the years of use of polycarbonate lens that seems that its just a useless invenstment comparing with zeiss glass that has such clarity.
dirb9 wrote:
AFAIK, they weren't plastic, they were normal spherical lenses made of glass with a strip of plastic glued to them to make them aspherical.
Actually, there is an all plastic one (#2), the type you mentioed plus 2 other types according to the Canon Camera Museum. I merely mentioned the plastic one since that's what this thread is supposed to be about:
1. a ground and polished glass aspherical lens element.
2. a molded glass aspherical lens element.
3. a molded plastic aspherical lens element produced by a high-precision molding technology.
4. a replica aspherical lens element, ultraviolet-light-hardening resin layer on a spherical glass lens element.
