Goggles 101

Discussion in 'Softgoods: Clothing, Helmets, Goggles, and More' started by Alexzn, Dec 2, 2016.

  1. Alexzn

    Alexzn Ski Squaw Skier

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    Alexzn's Googles 101

    So, you want to buy a new pair of goggles? Go to the store (or the your favorite online retailer), take a look at the boxes, or at the product page of the pair that you like. Admire the artfully written copy and carefully constructed diagrams of traced and split color rays. Take a deep breath. Most of this stuff is at best irrelevant and at the worst wrong. There are only two characteristics of a google that should matter to you, and one of them is almost never even mentioned in those descriptions. (There is also a third important parameter-fit-but we will talk about that later).

    The first parameter is VLT- Visible Light Transmission- number, which tell you how dark the lens is. Usually it is expressed as a percent of light that passes through the goggle. A VLT of 8 will be a very dark lens that transmits only 8% of the visible light, suitable only for very bright days, and a VLT of 70 will be a "storm" type lens that passes almost all the light through. Normal general-purpose lenses usually have VLTs at around 30 (20-40%), storm lenses tend to be at 60-85 VLT and really bright sunlight lenses are at 20 and below. If you can afford only one pair of goggles, it should be a general purpose lens, your second pair should be a storm goggle. Many manufacturers sell goggles with two lenses included, and in most cases it will be a general purpose lens coupled with a storm lens.

    Screen Shot 2016-12-02 at 12.15.38 PM.png

    Technical aside 1: Why do goggle lenses need to attenuate the light? Our eyes can detect well only a certain range of light intensities. When the contrast in a scene (the absolute difference between the bright and dark regions) is too high, the eyes stop seeing details in some of those regions. Cutting out a portion of the light preserves the relative intensity differences, but reduces the absolute value of the difference. Suppose, an eye can only differentiate between the values that are at most 1,000 units apart and we are looking at a scene with the sky at 2000 units brightness and shadows in front of bumps that are at 200 units. The contrast value of 1800 units is too much for the eye to handle, and as the result you don't see any details in those shadows. Now lets put on a google with a VLT of 20. Now we see the sky at 400 units and the shadows at 40 units. We now cut the contrast to 360 units, well within our initial 1,000 units "dynamic range" value. The eye can adjust to the reduced brightness and perceive the full contrast range of the scene.

    The second parameter is the lens material. This is something that manufacturers don't tell you, or if they do, they wrap it in impenetrable language of proprietary trade and marketing names that feels and sounds like cryptonite. Ptutonite, SR93, ChromaPop, Prizm, NXT, the list does on and on. In reality, an overwhelming majority of the lenses are made of only three materials. The cheapest googles are made for some sort of acetate polymer (those are the goggles where the lens is so thin that you can deform it with your fingers). That material is soft, easy to scratch, and has mediocre optical properties (this is why they have to make it so thin). Those google should only be bought as emergency throwaway replacements, if possible, so go for the better lens materials if you can afford it. By far the most common good goggle lens material is polycarbonate, which is a standard material for any sports - related optics. Every company, Oakley, Smith, Briko, POC, Zeal, etc. uses polycarbonate and calls it something else. It's a great material, clear, scratch-resistant, and light. A newer, and by all accounts better, lens material is Trivex, which has been popularized by the advent of rimless eyeglasses. It is significantly clearer (in fact as clear as glass), and just as scratch-resistant and shatter-proof as polycarbonate. So far only few companies use it in their higher-end goggles and nobody calls it Trivex. POC's NXT and Smith's ChromaPop lenses are Trivex. Anecdotally, all Kaenon's sunglasses have Trivex lenses, as well. If you afford a Trivex lensed google, I highly recommend it, the clarity difference would be noticeable.

    Technical aside 2: Why is Trivex Better? One of the key materials characteristics is its propensity to disperse the light of different color, which makes the features slightly blurry. Its is measured by the so-called Abbe number (the higher it is, the better the material is optically). The gold standard is glass with Abbe number of 42. Polycarbonate clocks in at 30, Trivex has the Abbe number of 43, virtually indistinguishable from glass. Some glasses such as crown glass, have even higher Abbe value of 59. Curiously, a common eyeglass lens plastic CR-39 has an Abbe value of 58, but, unfortunately, it is not considered shatterproof (at least I have not heard of goggle lenses made of CR39). One advantage polycarbonate has over Trivex is that it has a higher index of refraction, allowing for thinner eyeglass lenses, but that is irrelevant for nonprescription sunglasses or goggles.

    Lens tints. There is no other area that is so full of misconceptions and outright BS as lens tints. Every company claims to have a proprietary lens tint that increases contrast and give you magical powers to see through the fog, behind bumps, and right through the soul of your fellow skier. Most is just marketing hot air. The overwhelming majority of the lenses have reddish-yellow tint that is designed to remove light in the blue region of the spectrum and increase contrast (see Technical Aside 3 to why this works). The game is finding a compromise between maximizing contrast enhancement and minimizing overall color distortion at a given VLT. Smith and POC prefer to compromise on amber/sienna tints. Oakley recently went all out to the "more contrast" camp by coming out with the Prizm tints that are all VERY red. in general VLT and the lens material are much more important for the overall experience than the tint. (Note- never judge the tint from how the goggles look, always look THROUGH them. Mirror coatings are sometimes used to drop VLT further down, but usually they are there for aesthetic purposes, i.e. to make your goggle look cool).

    Technical aside 3: A single physical law is responsible to why the sky is blue and military tactical lights are red. The Rayleigh law says that the scattering efficiency of the light is inversely proportional to the 4th power of wavelength, which means that blue light scatters much more than red. This is why military uses red lights to read maps, to minimize the scattered light that can be picker up by an enemy. Scattered light robs a scene from contrast, this is why most goggle lenses are reddish. Red tints also darken the sky to reduce distraction for a skier. I suspect that this is all there is to the Oakley's Prizm technology. It is simple, but it works.

    Photochromatic lenses. Photochromatic lenses are lenses that change their VLT depending on the light conditions. This is desirable property that stretches the versatility of a google lens. POC NXT lenses are photochromatic with VLT that goes from 10-50. This is what I have, and although I have a dedicated (polycarbonate) storm lens, I all but stopped using it. The combination of convenience of adjustable VLT and increased clarity from Trivex makes it work well enough in every light conditions, and if the weather changes from foggy to sunny, I don't have to worry about switching goggles. Zeal also makes photochromic goggles. Smith makes photochromatic sunglasses, but I do not think they make photochromatic google lenses. One drawback is that tint adjustment takes time; thus, if you dive into dark trees form a sunny ridge, the lenses cannot adjust fast enough.

    Polarized lenses. Unlike hiking, fishing, sailing, hunting, or driving sunglasses where polarized lenses are desirable, skiing derives very little functional benefit from polarized lenses. The reason is that snow is composed of billion of tiny randomly-oriented ice crystals that scramble polarization of the reflected light. Polarized goggles ill still darken the sky and reduce reflections from foliage, but they would do nothing for the snow contrast. Don't waste your money.

    Goggle fit. This is a key point that a lot of people miss. If you wear a helmet (you should), buy the helmet first and then make sure that the goggle you buy fits your helmet in a way that there is no gap between the top of the goggles and a helmet (if you ever heard the term "gaper gap", this is it. Make sure also that the goggle does not pressure your nose and that the gap with helmet on the sides is not too big.

    [​IMG] Classic gaper gap

    Interchangeable lenses or separate goggles? Last few years saw a trend of manufacturers including an extra lens with their higher end googles and making the lens change much easier. It arguably started with Smith I/O goggles which promised (and delivered) easy lens changes in minutes for everyone. Arguably the coolest solution is Anon's M2/M3 googles where the lenses are held to the frame with 8 powerful rare earth rare earth magnets and can be changed in seconds. I am personally split on the utility of this approach, I would much rather just carry a second pair of goggles with me instead of messing around with lens switching on the lift, but many people like the increased compactness of having to carry only a lens in their pockets. A photochromic lens made it a mute point.

    Sunglasses or goggles? Many people ski in sunglasses because googles are too hot on a sunny day. Its a personal choice, but I would not recommend it for the following reasons:
    1. Modern goggles are vented very well. (As an aside, the rather "drafty" nature of the Smith I/O design probably contributed to their popularity as much as their pioneering design, because it virtually eliminated fogging).
    2. Sunglasses have a decidedly lower speed limit than googles. At higher speed your eyes will start tearing up if you wear sunglasses.
    3. Goggles are designed to protect your nose and face in a crash. Sunglasses frames can break and injure your face or eyes in a crash.
    4. Goggles have double lenses that reduce fogging. If you crash in sunglasses and get snow to cool the inside surfaces of your lenses, they will start fogging like crazy.
    5. Sunglasses may have glass lenses. Do NOT ski in glass-lensed sunglasses! Ditto for cheap sunglasses which may be made from wonderfully clear CR39 plastic which is NOT shatterproof.

    Durability and failure modes. Aside from crash damage the most common failure mode of goggles has nothing to do with lenses, they usually are retired when the face foam degrades, when the strap gets stretched too much and loses elasticity, of when the lens gets too many scratches. Another common mode is when the seal between the inner and outer lens sheet fails and moisture gets in between the lenses, giving rise to a royal size fogging issues. Smith's unique Porex filter design that they use in their lenses seems to be more effective in reducing those incidents, but other companies are usually very good at warranting this type of failure. Contrary to the conventional wisdom goggles are usually scratched when you not skiing, so keep them in a protective bag in your backpack and don't throw them on the lunch table.

    Happy (and clear-eyed) skiing!
     
    Last edited: Dec 2, 2016
    Posaune, Dave Petersen, pete and 16 others like this.
  2. crgildart

    crgildart Gravity Slave Skier

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    Goggles PhD... ManMade snow, blower conditions..

    If you ski some place making a lot of man made snow any goggle you purchase, regardless of price or fit, will ice over every time you ski or ride the loft past snow guns. You can cover them with your gloves to prevent some of this but you will find yourself having to scrape a layer of ice off of them about every couple minutes in the line of fire. I recommend a "Ski Gee" or similar type of scraper that you can wear on the thumb of your glove or mitten.

    [​IMG]
     
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  3. Yo Momma

    Yo Momma Out on the slopes Skier

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    This is approaching awarding a "Sticky" territory........ if that's done on here. I just picked up a set of Smith/Chromapop ( = Trivex - only now do I know this thanks @Alexzn ) lenses to replace my polycarbonate blue sensor mirrors which I use in 99% of conditions here in the northeast. Only on trips out west and late, late spring in the east do I switch to my Anon solar goggles. Thank goodness Smith was generous enough to make the new lens material in a retro-fit adaptation for my Prophecy's, so I could upgrade for <$100. Kudos to Smith as that fosters customer loyalty.... 3 Smith helmets currently on deck........ Great post......... Thank you for all the good info. I'll do a comparison once I've had a chance to check them out but outside around the house, when there was full snow coverage......... there was a VERY noticeable difference in contrast and clarity. I was actually surprised and expected much less of a difference.
     
    Last edited: Dec 2, 2016
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  4. Pete in Idaho

    Pete in Idaho Out on the slopes Skier

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    Yo, where did you buy the Chromopop lens ? I have been looking for a place where I can buy just the lens and put into my IO goggles, want the stormy day lens as we only ski in sunshine occasionally, like 5-10 per cent of the time. Do you have the sun or stormy lens and how do you like?


     
  5. David Chaus

    David Chaus Chain saw and wood chipper (kilt optional) Skier

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    I just checked the Smith website; you can order the Chromopop lenses through them, also online retailers have them available. The photochromatic lenses aren't yet available, though.
     


  6. Yo Momma

    Yo Momma Out on the slopes Skier

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    Through Backcountry.com: http://www.backcountry.com/smith-pr...ferralID=bbac842a-b91d-11e6-9012-0050569451e5

    In the "Select your style & size" pull down menu, scroll to the bottom and you'll see the various options for Chromapop Storm/Sun/Everday........... Check for your particular I/O goggle on there, as this link is for the Prophecy goggles you see on my head in my avatar. Good luck. These are hot items so act fast if you find them in stock! :beercheer:
     
  7. Yo Momma

    Yo Momma Out on the slopes Skier

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    Tried out the Smith Chromapop Storm yesterday. At first, very subtle difference from my Blue Sensor Mirror lens. As the day went on, I found I was skiing w/ more caution than usual. I pinpointed it to the fact that I could actually clearly see all the varieties in the terrain topography. While in the lodge I verified this by comparing the lenses back to back. While the difference in the two lenses did not "Pop" out, over time I found that my experience involved less strain on my eyes, clearer visual acuity, and an overall apparent but subtle feeling of being more "in touch" w/ my environment. Don't expect a huge difference at first........ but over time I realize that this jump in quality is worth the price of admission.
     
  8. Uncle-A

    Uncle-A In the words of Paul Simon "You can call me Al" Skier

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    Does anyone have knowledge or experience with Zeal Goggles from Bolder Co. I saw a pair for a low price but know nothing about them so I did not get them but they may still be available in a day or so looking to get some feed back from the community.
     
  9. Philpug

    Philpug Enjoying being back on two wheels. Admin Pugski Ski Tester

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    I have used Zeal's w/o any disappopintment.
     
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  10. coskigirl

    coskigirl Making fresh tracks Skier

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    I liked my Zeal goggles. I’ve loved my Zeal sunglasses.
     
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  11. TahoeCharlie

    TahoeCharlie RetroMan Skier

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    I have used Zeal Photochromatic for about 5 years. While they worked ok, I found them to not lighten up enough for me in overcast conditions, I had to use another goggle for those conditions, I think VLT was 20 to 40?. This year I got a new helmet, Smith, and so decided to get new goggles, Smith CromaPop Photochromatic; after hearing all the rave reviews here and else where. IMHO the CromaPops are vastly superior to the old Zeals, much better visual acuity and much better "low light performance" as the range is 30 to 55 VLT.
     
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  12. richddt

    richddt Booting up Skier

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    I have been using POC NXT Photochromatic, I have a pair of M2 and IOX, but neither of them match the convenient and the snow definition of my POC.

    especially when you dashing in and out of the trees.
     
  13. coops

    coops Booting up Skier

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    The 'usual' - Amazon is worth checking up periodically.
    While over in the US, I got a new lens for my I/O 7's from them - i'll keep my 'old' and very good red sensor photocromatic, and the new rose flash chromapop photochromatic is even better.

    Julbo also do very good photochromatic lenses (NXT also).
     
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  14. PTskier

    PTskier Been goin' downhill for years.... Pass Pulled

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    prolens.com is a good place to buy lenses and complete goggles.

    I slightly disagree with the tint part of the original posting. I've compared my old Smith RC36 lenses with very similar Smith ChromaPop lenses. The new-tech ChromaPop show more contrast in the snow to my eyes. No doubt about it. My Dragon Lumalens new-tech lenses are among the few that definitely shows more contrast, the best I've owned. My Oakley Prizm Rose lenses are pretty good (better than RC36), but not as good for me as ChromaPop or Lumalens.

    Dim red light is used at night for map reading, etc., because it does not harm one's night vision the way white light does.
     
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  15. pete

    pete not peace but 2 Beers! Skier

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    too funny on your "more caution than usual"

    I've as well as spouse MJ have determined that we often ski better in poor visibility conditions as we were too blind to see the cut up conditions and relied on skills untrusted.

    I've felt at times while struggling in fair conditions that I should close my eyes ....ogsmile


    Great article @Alexzn !
     
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  16. Beerman

    Beerman Booting up Skier

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    I've been doing a lot of homework on Goggles and optics in the last 6 months. This is my take on the current offerings and general market offerings.

    Lens colour/tint research for snow conditions has improved dramatically in the last few of years, with most major brands stepping up their range of lenses. All claim to have some brilliant combination of tint/coating to see better than the opposition. Thankfully the research and efforts put into lense tints have improved, and I don't think anyone would contradict this. Some favourite lenses have been discontinued, not always a good move, as the manufacturer may disenfranchise some existing customers. Other tech has come along with heated lenses for de-fogging etc, although this tech has been used in other industries for years/decades, this is still in it's infancy for the snow industry, so refined solutions are still coming.

    As a general trend in lense tech, it appears as if a red/rose base, as mention in the OP from @Alexzn, is what most manufacturers are heading for, to increase snow contrast. Different VLT's provide for various light conditions, and coatings differ for that cool "can't see my eyes" look. If money is going to be thrown around for a new pair, my suggested order of importance for selection would be
    1. Fit, no one wants to wear something uncomfortable.
    2. Lens comfort, is the lense too dark or too bright.
    3. Area of vision. What is the peripheral and vertical range of a particular frame
    4. Spare lense/ease of change out
    5. Fog free
    And dead last on the list, Style.

    I recently got to try on a brand of photochromic European Goggles that currently claim to have the largest VLT range for a single lense. These lenses also swing out from the frame, especially good for up hill, fog free exertion. I really liked these goggles, but did they just did not fit. Disapointment was an understatement, and have had to keep looking. However, I liked the lenses so much I bought a pair of their sunglasses.

    Is the new lense tech worth the extra $$, well that comes down to your budget, but for the price of a day ticket at a large US resort, i think it is.
     
    Last edited: May 12, 2018
  17. fatbob

    fatbob Out on the slopes Skier Inactive

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    Quite liking the Dragon approach - they've made their new higher contrast lenses available acroos the board not just in a couple of top end frames.
     
  18. cantunamunch

    cantunamunch Meh Skier

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    This sounds like a nordic goggle. I've been going on about nordic goggles and nordic visors for a while now. Examples:
    Julbo Sniper
    Briko Move Up
    Casco Spirit
     
  19. DanoT

    DanoT RVer-Skier Skier

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    One thing that is probably worth discussing here is lens distortion.

    When a lens is bent to make it curved, the lens material is stretched at the bend point, making the lens material thinner at the bend and thicker where it is flat and not bent and looking through this type of lens causes distortion. The solution is to create a spherical lens that is bent (stretched) in two directions so the lens is effectively the same thickness throughout, eliminating distortion. The only problem is that a spherical distortion free lens is more expensive to produce than a bent in one direction cylindrical lens.

    Smith (and possibly some other manufacturers) make their own lenses and what they do is manufacture a lens so that it is thicker at the bend points before bending and then when it is bent and stretched and made thinner in only one direction, the new thinner thickness at the bend point matches the unbent lens thickness and thus a lower cost lens (only one bend) is produced with uniform distortion free thickness throughout, for less cost.
     
  20. MarkP

    MarkP Getting off the lift Skier

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    Different season, same concept... okay, the conditions weren't a factor.
    upload_2018-5-12_11-52-52.jpeg
     
    Last edited: May 12, 2018

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