Ski Goggle Science Part 2: Hints on tints

May 16, 1:38 PMSkiing ExaminerEric Wagnon

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Smith Optics offers a wide variety of lens tints for its goggles.
                                                                Photo: Smith Optics

Color my world

If we lived in a black-and-white world, the discussion of ski goggle lenses could basically start and end with visible light transmission (VLT) and polarization. Remember from Ski Goggle Science Part 1 that visible light has different wavelengths that eyes perceive as color. Blocking or allowing certain wavelengths through colored tints are a big part of the formula.

“By adding a tint, you enhance contrast and enhance your visual acuity. In the end, you take away tint and get more VLT, add tint reduce VLT,” describes Greg Randolph, communications manager at Smith Optics. “The balance is like baking a cake. You find what works and tastes, that is performs, best.”

Grey is considered a neutral tint in that it reduces VLT across the spectrum, so the eye does not perceive an added color. Most goggles designed for sunny conditions use darker brown tints. For example, the Smith Sol-X lens has a sienna brown tint that results in a VLT of 10 percent, meaning it lets through only 10 percent of the visible light. Adding a gold mirror finish to the Sol-X knocks down the VLT even more to 7 percent.

For overcast, flat light days, the goal for most goggle manufacturers is to filter the overabundance of blue light in those conditions. Yellow or rose tints with a very high VLT up around 70 percent are most commonly used for this purpose.

The reason a yellow lens works to eliminate blue light may be explained by a combination of anatomy and color theory. Receptors in the eyes respond to the primary colors of red, green and blue, often referred to as RGB. In a certain mind-bending sense, any object is intrinsically every color except the one the eye sees. For example, a red ball absorbs all light waves except the red ones that are reflected back and perceived by the eyes. A transparent filter such as a tinted lens works the same way in that a red filter, for instance, absorbs green and blue light while allowing red to pass through it. In RGB color theory, yellow, a combination of red and green, is the exact opposite of blue, making them complimentary colors. Therefore, a yellow filter allows red and green light to pass through to the eyes while absorbing only the blue.

“For Oakley, High Intensity Yellow is the pinnacle of low-light lenses for those guys,” said Hud Knight, director of merchandising for online retailer Backcountry.com. “Then the rose, orange is a little bit of a crossover where you’re going to survive if it gets brighter out.”

With Smith goggles, Randolph suggests the Sensor Mirror lens for flat light. The lens has a VLT of 70 percent with a light rose base tint and additional tint as part of the mirror finish. “Mirrors are essentially microscopic flakes of metal which can be colored or plain. The mirror coating reduces VLT, but also has an effect on the overall tint as the mirror coating can be colored itself,” he explained. “For the Sensor Mirror lens, our flat-low light lens, the metal is actually slightly tinted in the rose spectrum which affects the color of the lens and its ability to add contrast, as well as reduces VLT to a level which we found was ideal.”

The I/O series of goggles from Smith features interchangeable
lenses.                                                      Photo: Smith Optics

For a versatile all-around Smith lens, Randolph singled out the Ignitor Mirror as the best option and called it, “a little more refined than RC36,” Smith’s older all-around lens, named for its rose and copper tints, producing 36 percent VLT.

“We actually developed Ignitor for sunglasses initially,” Randolph said. “We developed it for a nice bluebird day to being in dark timber or a rainy day. For the goggles, we tweaked it and added a bit more rose.”

Changing on the fly

Smith’s I/O goggles include both a Sensor Mirror and Ignitor Mirror lens that can be changed out fairly easily when conditions change. Two movable clips along the top of the lens are used in changing the lenses.

Giro also has an interchangeable lens system with the Manifest goggles. Two lenses, one for low-light and one for medium to bright light, are included with the Manifest goggles. The lenses may be switched out by using the “Pop Top” technology that is unique to Giro.

The Scott Natural lens is designed to provide definition and
contrast without adding a strong color tint.
                                                                 Photo: Scott USA

Going natural

Goggle manufacturer Scott has shifted away from using obvious tints in its Scott Natural lens series. At first glance, the lenses appear to be a neutral grey, but the concept is to use subtle colors to achieve clarity and contrast without adding a dominant color. “The trick is educating the public that contrast is the key to ski or ride,” said Gabe Glosband, director of marketing at Scott. “The assumption would be that it’s just a grey lens, but it’s a very pleasing lens to wear and gives you plenty of clarity and contrast. We’ve had a really strong response. It produces a neutral look that’s less offensive to the eye.”

Three Scott Natural lenses are available for the 2009-10 season: the Natural Transmitter (48 percent VLT), the Natural Light (35 percent VLT) and the Natural Elevation (15 percent VLT). While the Natural Light lens was new for 2008-09, the Natural Transmitter and Natural Elevation are new for next season.

Eye of the beholder

The challenge for goggle makers is that eyes and perceptions are different. For instance, the eyes’ own lenses slightly yellow with age. “Ideal is not uniform. Kind of like opinions and eyes, everyone has them and they are all different,” said Randolph, who tests goggles at Sun Valley Resort near the Smith Optics headquarters. “There is no one best lens for everyone, but the art is making lenses which address most people's needs. I think the success of our lenses indicate that we have done a solid job of finding what works best for most and creating multiple options that allow people to discover their preferred lens.”

World Cup racer Julia Mancuso uses POC goggles. The
Swedish company has a model named for the U.S. skier.
                                                                              Photo: AP

Even blue lenses made by POC may be seen on World Cup racers. While blue light has traditionally been seen as the enemy (see Ski Goggle Science Part 1), POC defends its unusual tint. “Although there is some logic in the assumption that a blue lens is not good in flat light conditions, we get a lot of feedback that blue lenses work great and are actually preferred by many customers, both at the pro and leisure level,” replied Oscar Huss, POC product process manager, from the company’s headquarters in Sweden. “It almost touches a philosophical field, but actually what is blue for someone might be perceived different by someone else.

"Some recommend yellow, while others claim red or rose to be the best, maybe depending on what kind of light perception their product manager or test team has," he added. "Clearly there is not a best practice here. If there were, we and all others would use the same. Our contribution is to try to offer many good choices.”

The bottom line

While a formal goggle demo system is not really in place, the best advice is try different lenses actually on the mountain in different light conditions, perhaps by trading with a ski companion for a run. Conflicting theories and opinions do indeed exist among goggle makers and skiers. However, everyone agrees that being able to see the contours of the terrain makes skiing much easier and more fun.
  

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