(from overboardboater.com, Nov 10 2009 -- italics added by Ruby Creek)
REVIEW: Costa 580 Silver Mirror Lenses
For scientific purposes, on a recent fishing outing I took off my shades and stared at the water. Clouds rolled in, obscuring the surface with their reflection and magnifying the glare. I put the shades back on, a pair of Costa Del Mar Zane glasses with 580 Silver Mirror Lenses. The vegetation and underwater contours of the shoreline popped as if on a big flat screen HD.
The whole purpose of lens polarization is to reduce glare, caused by how light waves bounce off a flat surface like, say, water. These waves reflect back to your eyes along a horizontal plane. Sunglass makers combat this by making lenses with vertical polarization filters that block the reflected light, cancelling out glare. This can be done on the cheap by spraying a thin chemical film on surface of the lenses, like you'd find on drugstore shades. Or it can be encapsulated within the lens, as Costa does with its 580 glass lens technology.
Costa calls them 580 lenses because they block yellow light, the hardest for the human eye to process, at 580 nanometers. (Visible light ranges from about 390 to 780 nm.) The result is they enhance the remaining light and give you that feeling that the whole world is coming at you in vivid detail.
The 580 technology has been around for a few years, but what I noticed about the new Silver Mirrors is how well they worked in low light conditions. I could pick up things at dawn and dusk or on overcast days that I missed when I threw on other high-quality polarized glasses. Costa says the Silver Mirror lenses let in more natural rays, with 12 percent light transmission compared to 9 percent for other lenses.
In an age of ridiculous over-specialization, the 580 Silver Mirrors are also versatile. They served me well both on a lake and searching for pelagics 40 miles offshore, and in a variety of conditions. (I could actually see better with them on while driving in the rain.)
The nylon Zane frames, named after the Zane Grey Reef in Panama (named after, well, Zane Grey), are updated versions of the popular Fathom style. The price tag will scare people off; some will have a hard time shelling out $239 for an item they're guaranteed to lose, drop overboard, or step on. But the hi def view may be worth it.
For more information visit www.costadelmar.com