The catch, of course, is that as the coatings get more high-tech and complicated, the cost of putting those coatings on a lens increases exponentially. Compounds can be deposited directly onto a prepared lens or embedded into a microscopically thin film that is affixed to the lens; it just depends on the compounds, the lens, and where and how it is to be used.

"There are three or four different coating processes used for applying optical coatings," Smith said. "Evaporative coatings, e-beam assist, ion-assisted deposition, and ion-beam sputtering are some of the processes we use at Leupold. IAD and IBS produce the highest quality and most dense coatings. These are also more expensive, as the equipment to deposit them is more expensive."

After the beams have finished assisting and the ions quit sputtering, the resulting coatings not only reduce reflectivity and produce a bright, clear image, but they are extremely hard and durable. The armored lens is less susceptible to abrasions and scratches that, over time, would rob its ability to transmit light in the manner engineers like Smith worked so hard to accomplish. This quality is so important, the U.S. military has sought to quantify it and requires optics to meet or beat an abrasion test. As an example, Leupold's DiamondCoat 2 coating withstands the requirement of 500 rubs of steel wool without scratching and meets the military's standard of a hard, tough lens.

Some optics makers have coatings that can repel water and resist fogging, while other coatings on specialized equipment work to improve light from parts of the spectrum unnoticed by the human eye. The cost for these sometimes-important features can be measured in their effect on light transmission.

Unfortunately, simply tipping up an optic and catching a green or red or yellow hue off the objective lenses will tell you very little about the quality or technology contained within. In the most general of generalities, the more coatings an optic has, the better. Multi-layer coatings are superior to single-layer coatings, while fully coated, index-matched coatings are the best, although quantifying coating quality would sorely test the skills of even the most enlightened optics enthusiast. And since every human eye sees light differently, about the only way to really get a feel for a scope's lens-coating quality are side-by-side comparisons.

Look through an optic into shadows, at areas of bright light and at various colors--the brighter the image, the better the coating. View an object or target with alternating black and white bands and you can quickly see the difference in resolution or dispersion (color separation) if the black/white edge appears smeared or purple.

Unless you are an engineer like Smith, lens coatings are a little less than exciting. But they have elevated the common riflescope from a sunny-day novelty to a tool that can be used from first to last light.