Modern lens coatings perform far beyond the original anti-reflective coatings invented in 1935 by a Carl Zeiss engineer. They reduce reflection to almost zero, transmit an extraordinary amount of light, and fine tune that light so that color transmission is near perfect as well.

Though not nearly as glamorous as ballistic compensating reticles or new side-focus knobs, a scope's lens coatings are essential components of that optic's ability to transmit the available light to a shooter's eye, tune the color of that light, and protect expensive lenses from the elements. With the exception of the quality of an optic's glass, coatings might just be the most important part of a bright, clean, and clear image.

In 1935, a Ukrainian physicist named Alexander Smakula invented anti-reflective lens coatings while working for Carl Zeiss. His single-coating treatment dramatically improved the performance of a wide range of optical instruments.

Smakula understood that light, like many forms of energy in nature, traveled through the air as a wave, and when that wave met glass, a certain portion of the wave was bounced back as a reflection. The reflection not only distorted the image but robbed the viewer of a fraction of the overall light being transmitted. This happened every time the light entered and left a lens. If the glass surface were coated with the right material to the right thickness, the reflective wave could be tuned, in a sense, so that the incoming and outgoing waves canceled out one another. A clearer image with less distortion and more light transmitted through the lens were the results of Smakula's early experiments with anti-reflective coatings, and the world was suddenly a better place--especially when viewed through a binocular or riflescope.

More than 70 years later, lens coatings are standard on just about every piece of glass that comes between the human eye and a distant object. A host of exotic materials and more exotic means of applying those materials to glass have evolved, as have the number of coatings that are stacked on a lens. Scott Smith has a graduate degree in optical engineering and manages Leupold's R&D and design engineering departments. His work centers on delivering the best possible image to the eye, and much of that optical sorcery is accomplished with lens coatings.

"If you take a single lens made of glass, it has two surfaces," Smith said. "If there is no coating on that lens, you lose four percent of light transmission per surface--or eight percent per lens. In a riflescope with 10 elements, you would have at least 20 surfaces with four percent loss per surface. So you can see how this adds up very quickly and why it is crucial to use anti-reflection coatings."