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Re: [John Muir Trail] Re: Polarized Lenses

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  • Ned Tibbits
    Julbo has been a sponsor of Mountain Education for the past three years and whether we are ski patrolling or ski-mountaineering in the high sierra they have
    Message 1 of 11 , Jun 21, 2013
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      Julbo has been a sponsor of Mountain Education for the past three years and whether we are ski patrolling or ski-mountaineering in the high sierra they have served us well, design and function!
       
      Ned Tibbits, Director
      Mountain Education
      www.mountaineducation.org
       
      Sent: Thursday, June 20, 2013 2:21 PM
      Subject: [John Muir Trail] Re: Polarized Lenses
       
       

      Thanks for taking the time to write all of that up!

      I agree that polarization makes sense for backpacking. That warning from the vendor I'm using regarding impairment of accurate judgment of terrain just got me worried that I might be making a mistake.

      One of the main reasons I'm buying new sunglasses for the trip is precisely because of the issue of light coming in through the sides and top of my casual everyday sunglasses which are also polarized. These sunglasses work fine for backpacking in East Coast forests but I suspect they will be inadequate in the Sierra at elevation. I have tried overglasses and did not find them very comfortable so I'm going to have prescription lenses made. I'm probably going to go with the Jublo Colorado frames which seem to fit me the best of all the Jublo line at REI and they have removable side shields so I won't look totally ridiculous if I wear them in casual use on the street.

      --- In mailto:johnmuirtrail%40yahoogroups.com, "john_friend" <yahoo@...> wrote:

      >
      > Here's some info to help
      you understand how polarized sunglasses work.
      >
      > All light rays
      consist of a particular plane of polarization. You can think of a light ray as having an orientation to it (up/down, left/right or any particular angle to it. Polarized sunglasses are made to block 100% of a particular plane of polarization.
      >
      > Light coming directly from the sun has random
      polarization. That means that every light ray (or photon to be technical) has it's own, completely random plane of polarization. If all the light stayed randomly polarized, then polarized sunglasses would block about 1/2 the light. All by itself, that would be fine. You'd have sunglasses that blocked half the light.
      >
      > Now, when light bounces off something and is reflected
      such as bouncing off light colored granite or particular bouncing off the surface of water, the random polarization becomes much more aligned all in one particular direction. The orientation of the polarized sunglasses is made to block all of this light that is reflected off a polished surface directly in front of you. In this case, polarized sunglasses will block way more than 50% of the light. They will block nearly all the reflected light and 50% of the non-reflected light. You WANT to block a lot of the reflected light because it's really just glare so this is good.
      >
      > In addition, some of the
      light coming through the atmosphere at certain angles also obtains a particular plane of polarization (no longer random). Your polarized sunglasses (when at just the right angle) will block a lot of that light too. You can often see this effect by rocking the orientation of your head from side to side when looking at the sky/horizon. At one particular orientation, the sky will be a lot bluer and there will be a lot more contrast with the clouds. This effect isn't quite as useful for sunglasses because the angle of maximum blockage isn't always just right for your sunglasses, but it is why using a rotating circular polarizer on your camera can really, really help the contrast of your pictures (I will be carrying one for my Fuji X-E1 camera on my JMT trip).
      >
      > So, the
      conclusion here is that polarized sunglasses are GREAT for backpacking. At worst, they block 50% of the light and at best they block much more than that including many glaring reflections. This is also why they are great for driving because polarized sunglasses can block 100% of the glare off the inside of the windshield when the dash is in bright sun.
      >
      > The other thing I'd
      suggest is to make sure whatever glasses you get have good bottom and side coverage. As there's a lot of reflected light off granite surfaces, you don't want a lot of light reaching your eyes from below or to the sides of the glasses. This won't be direct sunlight, but it can still be very bright. It often bounces off your skin, then off the inside of the glasses and then into your eyes reducing the contrast you can see and annoying your eyes. This is why many pro athletes (like baseball players) wear the eye black under their eyes because it prevents the reflection off their skin from reaching the inside of their sunglasses. Hikers probably don't need that if you have glasses that cover enough of your face and fit well enough (enough wrap around the sides and tight fit below the eyes).
      >
      > I'm absolutely wearing polarized
      sunglasses on my JMT trip and wouldn't consider wearing non-polarized.
      >
      > --John
      >
      > --- In
      href="mailto:johnmuirtrail%40yahoogroups.com">mailto:johnmuirtrail%40yahoogroups.com, "ravi_jmt2013" <ravi@> wrote:
      > >
      > > I am getting ready
      to order prescription glacier glasses this week and have encountered some conflicting information regarding the pros and cons of polarization.
      >

    • Viraj Ward
      I second the opinion on the Julbo s. They provided superior side protection when I hiked on those long snow fields in 2011. Viraj Ward Sent from my iPhone
      Message 2 of 11 , Jun 21, 2013
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        I second the opinion on the Julbo's. They provided superior side protection when I hiked on those long snow fields in 2011.
        Viraj Ward

        Sent from my iPhone

        On Jun 21, 2013, at 1:09 PM, "Ned Tibbits" <ned@...> wrote:

         

        Julbo has been a sponsor of Mountain Education for the past three years and whether we are ski patrolling or ski-mountaineering in the high sierra they have served us well, design and function!
         
        Ned Tibbits, Director
        Mountain Education
        www.mountaineducation.org
         
        Sent: Thursday, June 20, 2013 2:21 PM
        Subject: [John Muir Trail] Re: Polarized Lenses
         
         

        Thanks for taking the time to write all of that up!

        I agree that polarization makes sense for backpacking. That warning from the vendor I'm using regarding impairment of accurate judgment of terrain just got me worried that I might be making a mistake.

        One of the main reasons I'm buying new sunglasses for the trip is precisely because of the issue of light coming in through the sides and top of my casual everyday sunglasses which are also polarized. These sunglasses work fine for backpacking in East Coast forests but I suspect they will be inadequate in the Sierra at elevation. I have tried overglasses and did not find them very comfortable so I'm going to have prescription lenses made. I'm probably going to go with the Jublo Colorado frames which seem to fit me the best of all the Jublo line at REI and they have removable side shields so I won't look totally ridiculous if I wear them in casual use on the street.

        --- In mailto:johnmuirtrail%40yahoogroups.com, "john_friend" <yahoo@...> wrote:
        >
        > Here's some info to help you understand how polarized sunglasses work.
        >
        > All light rays consist of a particular plane of polarization. You can think of a light ray as having an orientation to it (up/down, left/right or any particular angle to it. Polarized sunglasses are made to block 100% of a particular plane of polarization.
        >
        > Light coming directly from the sun has random polarization. That means that every light ray (or photon to be technical) has it's own, completely random plane of polarization. If all the light stayed randomly polarized, then polarized sunglasses would block about 1/2 the light. All by itself, that would be fine. You'd have sunglasses that blocked half the light.
        >
        > Now, when light bounces off something and is reflected such as bouncing off light colored granite or particular bouncing off the surface of water, the random polarization becomes much more aligned all in one particular direction. The orientation of the polarized sunglasses is made to block all of this light that is reflected off a polished surface directly in front of you. In this case, polarized sunglasses will block way more than 50% of the light. They will block nearly all the reflected light and 50% of the non-reflected light. You WANT to block a lot of the reflected light because it's really just glare so this is good.
        >
        > In addition, some of the light coming through the atmosphere at certain angles also obtains a particular plane of polarization (no longer random). Your polarized sunglasses (when at just the right angle) will block a lot of that light too. You can often see this effect by rocking the orientation of your head from side to side when looking at the sky/horizon. At one particular orientation, the sky will be a lot bluer and there will be a lot more contrast with the clouds. This effect isn't quite as useful for sunglasses because the angle of maximum blockage isn't always just right for your sunglasses, but it is why using a rotating circular polarizer on your camera can really, really help the contrast of your pictures (I will be carrying one for my Fuji X-E1 camera on my JMT trip).
        >
        > So, the conclusion here is that polarized sunglasses are GREAT for backpacking. At worst, they block 50% of the light and at best they block much more than that including many glaring reflections. This is also why they are great for driving because polarized sunglasses can block 100% of the glare off the inside of the windshield when the dash is in bright sun.
        >
        > The other thing I'd suggest is to make sure whatever glasses you get have good bottom and side coverage. As there's a lot of reflected light off granite surfaces, you don't want a lot of light reaching your eyes from below or to the sides of the glasses. This won't be direct sunlight, but it can still be very bright. It often bounces off your skin, then off the inside of the glasses and then into your eyes reducing the contrast you can see and annoying your eyes. This is why many pro athletes (like baseball players) wear the eye black under their eyes because it prevents the reflection off their skin from reaching the inside of their sunglasses. Hikers probably don't need that if you have glasses that cover enough of your face and fit well enough (enough wrap around the sides and tight fit below the eyes).
        >
        > I'm absolutely wearing polarized sunglasses on my JMT trip and wouldn't consider wearing non-polarized.
        >
        > --John
        >
        > --- In mailto:johnmuirtrail%40yahoogroups.com, "ravi_jmt2013" <ravi@> wrote:
        > >
        > > I am getting ready to order prescription glacier glasses this week and have encountered some conflicting information regarding the pros and cons of polarization.
        >

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