Water Torture

Water Torture

How optics makers are helping us see better--rain or shine.

The left side of this lens is coated with Zeiss's Lotu­Tec. Notice how the water beads as compared to the untreated side. This beading action allows water droplets to slide off the lens for a clearer image.

Over the years, to make binoculars and riflescopes more rugged manufacturers have used improved adhesives and mechanisms to strengthen mountings of lens groups and adjustments. They've replaced spider-web reticles with etched glass and have found ways to fashion one-piece tubes and seal in nitrogen and argon gas to prevent fogging.

Then, after decades of working inside the scope, they took another look at the outside. "At Bushnell, we concluded that fog-proofing is only half the battle," says Bill Cross, who has been designing optical systems for many years. "The other problem is fogging outside, from your breath and sudden changes in temperature. Rain and snow obscure your vision, too."


So in the mid-1990s Bushnell began offering RainGuard, an exterior lens coating so slippery that water can't easily adhere to it. It beads up and runs off.


"Look closely at even high-quality lenses through a powerful microscope," says Bill, "and you'll see tiny pits. These enable water to cling. Our hydrophobic RainGuard coating fills the pits and leaves a surface on which the water just can't get traction. It's also a scratch-resistant surface because grit and hard objects can't find a place to imbed. They slide right off."

A third generation of RainGuard now appears on Bushnell's best binoculars and riflescopes. RainGuard HD is also oleophobic, meaning it sheds oils too.


Another effective water-repellent coating is LotuTec, offered by Zeiss on its high-end Victory series. The name derives from the "lotus flower effect," which Zeiss explains as the hydrophobic characteristic of surfaces that encourage water to bead up and run off.


"LotuTec increases the contact angle of water droplets," says Zeiss engineer Walter Schwab. "Instead of sitting on the lens in a dome, a droplet pearls up in a sphere. Its base is smaller than its diameter, its height greater than that of a domed droplet. Because it has little purchase on the coated lens, it moves off.

"Because it takes the form of birdshot, water remaining on the lens has minimal effect on your sight picture. The distortion imposed by dome-shaped drops and subsequent water stains on uncoated lenses is much more disturbing."

Actually, LotuTec is three coatings that work in concert to prevent mechanical damage as well as shed water and oils. It has performed exceedingly well in my field tests.

StormCoat is a Burris lens treatment, introduced on Xtreme Tactical riflescopes in 2008 and now on its way into Euro Diamond and Black Diamond hunting models. According to Patrick Beckett at Burris, it is very effective in shedding water and fending off the grit from your shirttail.

"A lot of damage to scope lenses comes at the hands of their owners," he says. "In the field, we're all tempted to wipe dust or rain stains off a lens with whatever is handy. Repeated rubbing with abrasives harms glass. StormCoat resists scratches but doesn't affect brightness."

About a decade ago, Burris offered Q-Coat, a very durable film that also shed water but cost two to three times what the lens itself did and put the retail price of Q-Coated scopes out of the reach of most hunters. By contrast, Beckett says, StormCoat will become increasingly available on top-end Burris riflescopes without boosting their prices.

Patrick allows that while StormCoat and similar treatments are worthwhile options, they're not a panacea.

"We still use the wipers on automobile windshields coated with Rain-X--which, by the way, has figured into the development of scope lens coatings," he says.

He emphasizes that scope lens covers offer the best protection from the elements. "They also ensure that you get all the resolution and brightness you pay for," he says. "Even a thin film of dust on an outside lens will impair your view--especially if you must aim toward the sun. A cheap scope with a clean lens will outperform the most expensive scope with rain stains or dust on its glass."

Are there liabilities to water-repellent coatings? Not really, though they may be a bit more vulnerable to gun-cleaning solvents--which you'd best be keeping off lenses anyway.

How do you test optics you might wish to buy but whose descriptions make only vague reference to water resistance? Carry a small bottle of clean water with an eye-dropper cap. A single drop should bead and scoot off the glass if you tip it. Or squeeze a shot of fine mist from a spray bottle. The water should not streak but bead up like shot. If you breathe on a cold lens, the fog should quickly become tiny pellets.

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

Black Hills Evolution of Rifle Cartridge: .308 Win. 175 Gr. Match

Black Hills Evolution of Rifle Cartridge: .308 Win. 175 Gr. Match

David Fortier talks with Jeff Hoffman of Black Hills Ammunition about the evolution of the .308 Win. 175 Gr. Match bullet.

Tactical Solutions Introduces New X-Ring Takedown SBR Rifle

Tactical Solutions Introduces New X-Ring Takedown SBR Rifle

Keith Feeley of Tactical Solutions sat down with Michael Bane at SHOT Show 2018 to talk about the new X-Ring Takedown SBR .22LR rifle.

All About .300 Blackout

All About .300 Blackout

The .300 Blackout is here to stay, and we take some time to look at new technology surrounding this cartridge. Next, we pit subsonic rivals against each other before stretching the legs of this CQB round out to 600 yards from a short 9-inch barrel.

Delta 5 - Daniel Defense

Delta 5 - Daniel Defense's New Precision Bolt Action Rifle

Those looking to explore precision rifle shooting without going broke will be well served by Daniel Defense's new Delta 5.

See More Popular Videos

Trending Articles

The Marlin Model 1895-.444 Marlin is a handy, powerful rifle capable of taking down elk, moose, hogs, black bear and deer. Lever-Action

Marlin Model 1895-.444 Marlin

J. Scott Rupp

The Marlin Model 1895-.444 Marlin is a handy, powerful rifle capable of taking down elk,...

Ruger introduced .300 PRC and 6.5 PRC chamberings for the Ruger Precision Rifle. Bolt-Action

Ruger Precision Rifle Now Chambered in .300 PRC and 6.5 PRC

Rifleshooter Digital Staff - April 27, 2019

Ruger introduced .300 PRC and 6.5 PRC chamberings for the Ruger Precision Rifle.

Wilson Combat's new Ultralight Hunter in .300 Ham'r puts the sport back in modern sporting rifles. MSR

Review: Wilson Combat Ultralight Hunter

Brad Fitzpatrick - March 18, 2019

Wilson Combat's new Ultralight Hunter in .300 Ham'r puts the sport back in modern sporting...

Browning's new X-Bolt Max Long Range rifle is an accurate rifle tailored for long range accuracy. Bolt-Action

Browning's New X-Bolt Max Long Range Rifle

Rifle Shooter Digital Staff - April 11, 2019

Browning's new X-Bolt Max Long Range rifle is an accurate rifle tailored for long range...

See More Trending Articles

More How-To


As a kid I watched hard for the mailman in midsummer, hoping every day he'd show up with the How-To

Rifle Shooter's Favorite Fall Moment

J. Scott Rupp - August 16, 2013

As a kid I watched hard for the mailman in midsummer, hoping every day he'd show up with the

When under shelter-in-place orders and not going anywhere, your vehicle should be fueled and ready to go in case things change. In this lesson, “Hollywood Weapons” host and former Green Beret Terry Schappert shares some tips on how to prepare your car or truck for the next time you might need it.

Shelter in Place - Prepare Your Vehicle

Outdoor Channel Public Service Announcement - April 10, 2020

When under shelter-in-place orders and not going anywhere, your vehicle should be fueled and...

During a shelter-in-place order scenario, you only want to leave your house when absolutely necessary. That's why “Hollywood Weapons” host and former Green Beret Terry Schappert has this lesson about the most valuable and nutritious foods to keep stocked in your pantry, so that you can weather the storm.

Shelter in Place – Quarantine Cuisine

Outdoor Channel Public Service Announcement - April 07, 2020

During a shelter-in-place order scenario, you only want to leave your house when absolutely...

Why repack your ammunition? There are several good reasons. Ammo

How to Repack and Store Your AR Ammunition

David Fortier - December 04, 2012

Why repack your ammunition? There are several good reasons.

See More How-To

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Get Digital Access.

All Rifle Shooter subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now