How good are CR-39 lenses?
It’s optical quality is almost as good as glass (and far better than all the other options we will look at), it is half as heavy as glass, it is much more resistant to shattering, and still very resistant to scratches. In ‘raw’ form, before cut to your frames – CR-39 lenses.
Are Transitions lenses any good?
Cost effective – Photochromic or transitional lenses can actually be quite cost effective. Protects your eyes – Transitional lenses do more than function as sunglasses. They actually filter out a good deal of the harmful UV rays emitted from the sun, leading to healthier and happier eyes.
Is CR-39 better than polycarbonate?
In comparison to polycarbonate, CR-39 provides vastly superior optics, rating just one rung below the material with the highest ABBE value: crown glass. If you choose CR-39 lenses you commonly find that UV-protection comes at an added cost because, unlike polycarbonate, they aren’t inherently UV-protected.
Is CR-39 scratch resistant?
Developed by PPG during WWII, CR-39, also known as plastic or hard resin, serves as a much lighter lens material (approximately 50% lighter) than glass. CR-39, however, is far less scratch resistant and often must be coated to improve its scratch resistant characteristics.
What does CR-39 stand for?
Columbia Resin 39
Polycarbonate Lens Impact Test An alternative material to polycarbonate is CR39 (Columbia Resin 39), a plastic polymer commonly used in the manufacture of eyeglass lenses. Unlike polycarbonate, CR39 requires a UV coating to be added to protect eyes from the sun’s harmful rays.
Does CR-39 have UV protection?
CR-39 does in fact block UV light, but only up to 360nm. I believe the big reason that CR-39 does not block up to 400nm by itself is the UV filter at that point would cause the lens to be tinted light yellow, which is cosmetically unappealing. “It’s not impossible.
Is CR-39 the same as polycarbonate?
Polycarbonate Lens Impact Test An alternative material to polycarbonate is CR39 (Columbia Resin 39), a plastic polymer commonly used in the manufacture of eyeglass lenses. Unlike polycarbonate, CR39 requires a UV coating to be added to protect eyes from the sun’s harmful rays.
Is CR-39 a glass?
CR-39 is about half the weight of glass with an index of refraction only slightly lower than that of crown glass, and its high Abbe number yields low chromatic aberration, altogether making it an advantageous material for eyeglasses and sunglasses.
What are the drawbacks of transition lenses?
Cons of transition lenses
- They darken and lighten to varying degrees depending on the brand. Some lenses also take longer than others to adjust to brightness.
- These lenses can take longer to adjust in cold weather.
- They don’t darken as well inside cars.
Is photochromic lens good for night driving?
Photochromic lenses aren’t very helpful for night driving. Light adaptive lenses primarily protect against sunlight, UV rays and blue light. They don’t activate indoors under artificial lighting or at night in the presence of headlights and streetlights.