« on: January 03, 2012, 08:12:50 PM »
Canon has patented some lenses with resin elements recently, they are plastic elements that go inside the lens where they will not be susceptable to scratching...
So far, as far as I know, they have only been used in the AF unit of DSLR's, not in a EF lens.
In their Technical Room, Canon states:
Canon uses four different type of aspherical lens elements now depending on the purpose;
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.
There are plastic elements in some of the EF-S lenses (which are a subset of EF lenses) - the EF-S 18-55mm f/3.5-5.6 USM Technical Report states that a molded plastic aspherical element is used, and I'd bet one is used in the IS version of that lens, as well.
Interstingly, that same technical report corrects a misconception which I suffered from (and Wikipedia suffers from the same misconception) - that the "S" in EF-S stands for "short back focus." According to Canon, the "S" in "EF-S" comes from "Small image circle."
Fascinating. And not to reheat the debate over "engineering plastic" and "polycarbonates" again - but I also find this disturbing. I very much doubt based on my personal experience with this that there is any plastic available that can render the optical qualities we've grown used to over the last 100 years or so. It just doesn't exist in reality no matter what stuff certain companies are trying to sell to consumers. I know this from eyeglasses. Everything plastic - I mean everything - is inferior in that domain. And when you try to buy glass lenses here in the States you get these blank stares as if you're stupid or suicidal ("but that is sooo dangerous!"). Well, suicidal to me is driving without 100% clear vision. And no matter how fancy the plastic it will not be 100% clear vision but distorted, impure and suffering from chromatic aberration. And thanks to the FDA I'm even forced to buy my Zeiss eye glasses abroad. Makes me angry.
And now reading that $1000+ camera lenses now come with that same kind of nonsense amazes me. Is there a complete list anywhere where they are using this stuff? Because I'll not be knowingly buying it. If this all continues it's maybe time to really save up and go Leica (while they're still around).