What are all these coatings on scopes, binoculars and spotting scopes?
Take a look at any optics company’s site and you’ll find some descriptions about lens coatings that help with abrasion resistance, clarity, light transmission, glare reduction and waterproof capabilities.
By Alan Clemons
Some of these coatings are proprietary, specially designed by or for the company’s products. Others might be common, or used throughout the industry, for specific purposes. But virtually all companies enhance the optical glass in their products with coatings that help increase light transmission by reducing glare and helping more light get through to your eyes, thus improving the quality of the image you’re seeing.
“The goal of the coatings on an optical system is to continue as much of the light as possible through the system so it’s not lost,” said Trent Marsh, of Hawke Optics. “Pretty much everyone’s transmission percentage is in the low 90s. If you see something that’s 99.99 percent then that may be one lens, but not in multiple lenses.”
Brad Brumfield, of Leupold, and Reinhard Seipp, general manager and COO of Meopta USA, concurred.
“Light transmission is a value that everyone in industry gives,” Seipp said. “Say my binocular has a 92 or 94 percent transmission value, but that’s kind of like the gas mileage on your car. That should be followed with the question of, ‘Under what conditions?’ because conditions are different for everyone.”
“There are very simple anti-reflection coatings and very complex anti-reflection coatings,” he said. “The more complicated coating … let’s consider the visible spectrum to be 300 to 700 nanometers, and I want to pass as much light as possible all the way across. The inexpensive coating will do well over a small subset of the 300 nanometers but not anywhere else. So you add more layers (to lenses) in your performance stack to get that better performance. The only thing that means to you is it costs more. But you get more transmission and a higher contrast.
“And that’s just the anti-reflection coating. On the outside of the scope there are some common exterior coating types. One is the water-repellent coating and the other is an abrasionresistance coating. You’re very rarely going to scratch glass. But the coating that is on the glass, yes, that is something you can scratch. So the high abrasion-resistance coatings, they help with that quite a bit.”
The DeerPASS scope was designed by a North American hunter for the North American hunter. Special care was taken to ensure that the multiple range finding system would function quickly, accurately and give hunters from the less seasoned to the most advanced a precision aiming tool for harvesting North American game.
Once setup the DeerPASS reticle allows quick and easy shooting. Simply bracket the Deer and use the aim point that the deer is bracketed between. Point and Shoot!