Can someone explain polarized lenses?

Discussion in 'The Haberdashery' started by millertime150, Aug 28, 2009.

  1. I know they cut glare but what are the difference between the different companies?

    Are cheap polarized sunglasses better than expensive ones?

    I noticed that
    Oakley says their polarized are 99%
    Maui Jim ?
    Kaenon 99.9%
    Rudy Project 99.9%
    Costa Del Mar 100%

    Does this mean Costa cut 100% glare and are therefore better than the rest?

    How about how they are polarized? Are some just a film layer and are some actually part of the glass?

    I am just trying to figure out if one company's polarization is much better than anothers.
     
    Last edited: Aug 28, 2009
  2. probably not the answer you're looking for- but I bought some louis vuitton sunglasses the other week, and the lenses are so crystal clear that it actually feels like i'm wearing prescription lenses compared to other brands- I know they're like a million times the price but they are seriously so much clearer
    I don't know whether this is due to the plastic being higher quality or the polarization though
     
  3. The polarization effect i believe comes from the coating on the poly lenses. the cheap glasses do not have quality lens, probably the coating is similar as the expensive brands.
     
  4. This brings back memories from physics class...

    If I remember correctly, polarized anything will block out all light if held together. If only one polarized part is there it blocks out only part of the light.

    Maybe Wikipedia has more information...
     
  5. I my opinion polarized lenses are the way to go!

    From Oakley:

    I can tell you that poorly "polarized" lenses actually block more than just glare. When Oakley first started offering polarized lenses they inadvertantly blocked the ability to see laser light (not good for military) but they've since corrected the issue.
     
  6. Polarized are the only way to go -- for driving, boating, walking around, etc. etc. etc. etc.

    If my informational sources are correct, cheap polarized glasses usually have a plastic film that is polarized, while the more expensive ones will have a laminate with polarized film between glass / plastic lenses...

    My favorite polarized glasses are from Wiley-X (those who've been deployed to an unpleasant sandy area of the world will probably recognize the brand). They have an assortment, but the one I linked to is the most "normal" looking (non-tactical).
     
  7. A little anecdote.

    I live in Pasadena CA at the foothills of the San Gabriel mountains. At the moment there is a wildfire raging. As I was driving north towards home today, I saw the smoke and clouds over the mountains. As devastating as it is, I couldn't help but notice the beauty of it. The heavy, thick smoke looked like a painting. It was made up of different shades of brown, orange and gold. From the top of the main mass there was huge white cloud. And towards the sides, it changed from the gold, orange-brown to different shades of gray, from light gray to steel gray, like heavy storm clouds. All of this against a backdrop of light blue sky. I know people throw the word "surreal" around a lot, but in this case it fits perfectly... it was like a painting, it didn't seem real at all, and it was beautiful.

    I took my sunglasses off (Persols with gray polarized lenses) to take a better look, and as soon as I did that, the beautiful painting was gone. It still looked heavy, but gone were the golds and oranges, bright yellows and the sharp contrasts. Now it was just a big mass of different shades of dirty grayish browns.

    Just an illustration of how polarized lenses can make such a huge difference.
     
  8. Correct. Some polarized lenses are nothing more than a spray on coating while others are internally polarized.
     
  9. Polarizing lenses will allow only light that is similarly polarized to pass through. If two polarizing filters are place together and rotate, they will become alternately opaque and then transparent again as the polarization first is in the same direction and then 90 degrees opposite.

    LCD displays use this effect to generate displays, by suspending crystals in a liquid behind a polarizing filter. An electric voltage (potential) will "polarize" the crystals opposite to the polarization of the filter, creating an opaque digit.

    Glare from reflections is filtered by polarizing lenses by the nature of the lenses to exclude light that is not polarized the same way; reflections are often randomly polarized, thereby the lenses will cut the reflected light. On your camera, a polarizing filter can be rotated to eliminate the surface reflection of the sun on water, allowing you to shoot subjects that lie beneath the water.

    LCD displays often appear black when viewed with poloriod sunglasses, depending on the orientation of the display versus the sunglasses.
     
  10. Well there you go, LagerLover has you covered as far as the polarization explanation goes. As far as sunglasses go, I can't tell you which company is better than which considering I have been wearing glasses since I was in the third grade. So any sunglasses I wear have to be of the prescription kind, but I can tell you this. There's no functional difference between sunglasses that are 99% polarized and 100% polarized. In fact, I really wouldn't be surprised if claiming 100% polarization is a marketing ploy.
     
  11. I never knew this and my first impulse was th say "Impossible! How would a spray-on keep the polarization in a uniform orientation?" But after a little thought perhaps they do the spraying in an electro-magnetic field that keeps the particles or droplets oriented. Do you know how it's done?

    Polarized light is light whose waves are aligned with each other. Un-polarized light (which we can call "randomly" polarized) has waves that are unaligned, oriented in all directions. (Here we are talking about alignment directions transverse to the direction of light wave travel.) The only light that gets past a polarizing filter is light that is aligned with the polarizing filter. Well, it is actually a matter of degree -- the more closely aligned, the more likely to get through. Light oriented at 90 degrees to the filter is blocked. Since most of the light all about us is unpolarized (not aligned in any one orientation) much of it, but not all, passes through the filter.

    Many reflections are polarized. This is because only properly oriented waves actually get reflected. In effect the reflection acts as the first of two polarizing filters. Our polarized sunglasses act as the second filter. Since the polarization of our sunglasses is, by design, oriented 90 degrees to the horizontal surfaces that do most of the bothersome reflecting almost all of that reflected light is blocked while much of the unreflected light passes through.
     
  12. Impossible? No they've been using anti-glare coatings on glasses for quite some time.
     
  13. Not the same thing. I have non-glare coating on my specs but they are not polarized.
     
  14. Or, some lenses are both polarized and have non-glare coatings.

    Tim
     
  15. That would be my guess. I don't know positively, though. I went to order a new pair of Ray Bans, and they offered two types of polarization with the same percentage- except one was twice as expensive as the other. That was how it was explained to me, one was sprayed on and one was a "true" polarized lens. Supposedly the spray coats are more prone to scratching.
     
  16. Forget I said anything then.
     
  17. Wiley-X does make some decent glasses. I've always kind of seen them as the poor mans Oakley's but they do have some good options and as others have mentioned all are impact resistant to the same level as the Oaks.
     
  18. There are three different things at play here. Polarization, A/R(anti-reflective or non-glare), and UV protection. Polarization, as has already been defined above, blocks waves not aligned with the filter, thus providing the wearer with clearer, crisper, less visually 'noisy' images. This is an internal feature in the lens. A/R coatings are applied externally, generally just to the back side, to reduce glare on the back of the lens coming in from behind or from the side. There are different brands of A/R with different prices, some combined with scratch and smudge resistance. Some of these, such as 3M's Scotchgard A/R, are proprietary and can only be applied by licensed labs thus demanding higher prices. The percentages advertised with lenses refers to UV protection. Nothing comes out of our lab with less than 96% of UV blocked. We test every lens individually as part of our QC. Polarized lenses, because they filter ALL incoming waves, genrally block more UV as well. For example, our polycarbonate lenses genrally block 97% of UV transmission, while the polarized lenses block 99%.
     
  19. So do you work for 3M?
     
  20. No sir, we have stock finished lenses with the 3M coating, but we can't apply their coating to our lenses we surface in-house. We send them out. Our lab is small, and we have no in-house A/R machine. So if we don't have your prescription in our stock lenses, or you need multifocals, we'd have to send them out if you want A/R.
     

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