SunGlass Information
Archive for the ‘Hunting Sunglasses’ Category
Actually you have three choices when it comes to lens composition: Glass, Plastic or Polycarbonate. All have advantages and disadvantages we will discuss each so you can determine which is best for you.
Glass lenses provide the best scratch resistance and highest optical clarity. They are, however, 2-3 times as heavy as plastic or polycarbonate lenses and, while they are tempered for impact resistance, can shatter or break if struck by an object. These types of lenses are suitable for people who value durability and clarity but are not great for people involved in high speed sports or activities where something could strike your lenses or face.
Plastic lenses are significantly lighter than glass lenses, and thus, may be more comfortable to wear for extended periods of time. Also, while not shatterproof, these lenses are also more shatter resistant than glass. Disadvantages include average optical clarity and less scratch resistance. These types of lenses are great for customers looking for a lightweight, affordable pair of sunglasses.
Polycarbonate lenses are shatterproof and extremely lightweight. Their primary drawback is that the material is very soft and is the least scratch resistant material used. These lenses are great for active people involved in sports. Because they are lightweight they will stay put when moving around. The shatterproof lenses will also provide protection from not only UV rays, but also impact from objects or in case of an accident or a fall.
Better frames (often called Hand-Made Frames) are made from Cellulose Acetate or Zyl, as it is often called. This is the material the optical world recognizes as the finest and over 90% of it is produced in Italy by a company named Mazzuchelli or by its sister company in Hong Kong. Cellulose Acetate is derived from natural cotton and wood fibers and is subjected to a process of steaming, coloring, molding and cutting to achieve the necessary characteristics: translucency, shine, fluidity, subtlety and rich color patterns. Cellulose Acetate is used to make colors as simple as black or tortoise shell in hundreds of variations, to special colors like Lipstick Red, Lime Green or colors that change depending on the angle you see them from, and everything in between.
A Zyl frame is composed of two main parts: the front and the temples. The two parts are made separately and then assembled after each part has been completed and inspected. Creating an optical quality frame is a labor-intensive process that can be carried out only by highly trained technicians aided by technologically advanced equipment. Optical quality frames can be used for either sunglasses or fitted with prescription lenses. They are perfectly symmetrical and will not distort vision when fitted with ophthalmic lenses.
When Italian materials are used in designer frames it is made by pouring liquefied Cellulose Acetate, in colors chosen and mixed into large molds where they cool and then harden. More complex colorations are produced somewhat like a sandwich: several colors, in separate layers, and permanently bonded together. Some special colors are made up of up to 4 separate and distinct color layers. The possible color combinations of these “laminates” are endless. As the precess of making the glasses proceeds, the material is skived, or shaved away, exposing these different layers and creating stunning visual effects.
The frames are then “tumbled” with teakwood chips for as long as a week to make them smooth. The frame is then hand polished using a wax and emollient shining cream then buffed to a high luster.
A good designer spends a great amount of time designing temples that are comfortable to wear and that blend seamlessly with the front., while imparting a special flair to the glasses. Depending on the particular style, you will notice many different shapes and sizes of temples in different collection. The handmade process on the temples is as painstaking as that of the fronts because the temples are specially color designed to match he patterns on the front.
Nickel Silver wire temple cores and barrel hinges are inserted into the polished temples using an ultrasonic machine that shoots them into the temple at the proper angle. The wire core can be adjusted by you, or an optician, to comfortably fit each individual customer.
In this two-part Blog, I will discuss the three main ways that non-metal sunglass frames are made. In this part I will discuss the first two types Injection Molding and Advanced Materials. In the next part will be devoted to explaining Hand-Made frames.
The least expensive method is made by Injecting a mold created from aluminum or highly polished stainless steel with liquid plastic. This material is petroleum-based products that begins in bead form. To add color, they are spray-painted and then glass coated and tumbled for shine.
Recently materials like Grilamid TR-90 have been developed to answer the need for lightweight and durable frames that offer optical quality not typically associated with typical injection plastics. This new technology has made it possible to make great looking frames that can, in many cases accommodate prescription lenses. A new material, Grilamid TR-90, is a Swiss Nylon Polymer that is melted and then poured into optical quality stainless steel molds. fronts and temples are produced separately. Once removed from the molds, they are hand polished and assembled before the lenses are fitted. The temple tips and nose pieces of many Grilamid TR-90 frames are made from optical grade rubber to add comfort and prevent slippage during strenuous activity. The end result is a frame that is lightweight, yet extremely durable and flexible.
When asked what sunglass qualities where important for Bowfishing Robert Grider, O.D. wrote this article that first appeared on Bowhunting.com.
#1 Polarization
Sunglasses must use true polarized lenses to remove the glare which hinders our ability to see into the water. Most polarized sunglasses are marked, if it is not clearly stated then they are probably not polarized. Please realize that like most things in life, there are different qualities of polarization and the more expensive the lenses the more likely they are of higher quality.
#2 Quality Optics
Try to make sure the sunglass lenses optics are of decent quality. I have seen countless cases where people present to my office complaining of headaches only to find that the poor optics of their sunglasses are the source of the problem. To test your glasses you can hold the glasses up several inches from your face while viewing a consistent grid like a sheet of graph paper and by turning the lenses slightly and moving the glasses slowly back and forth and up-down while looking for areas of curved lines and/or distortion of the distant pattern. Please understand that many of today’s wrap-around type of sunglasses will have at least some distortion in the very extreme side or periphery of the lenses this is unavoidable but you would like this to be as minimal as possible.
#3 Lens Tint
I am often asked which color sunglasses work best for bowfishing and to be honest, there is no single best color for every person and every shooting situation. Gray lenses tend to alter the color vision spectrum the least in relation to the human eye and make for a good all-around pair of sunglasses that might be used for other activities as well. (see Selecting the Correct Tint Blog)
#4 Ultra violet ray protection
Make sure the sunglasses you purchase have the ability to absorb 100% of the sun’s harmful ultra violet rays. Remember while on the water you are actually getting a double dose of UV, those rays directly from the sun and those rays that are bouncing off the waters surface. Significant exposure to UV rays has been shown to cause the serious eye damage such as development of cataracts and Age-Related Macular Degeneration which happens to be the leading cause of blindness for those over 65 years old.
#5 Glass or plastic lenses and a word on cost.
In general, plastic lenses (polycarbonate lenses) scratch more easily than glass lenses but they tend to weigh half as much as glass and are much more shatter resistant than glass lenses making them safer if used around flying objects (think snap-back of an arrow). Many plastic lenses will have a scratch resistant coating with the more expensive plastic lenses having a better scratch resistant coating. Both plastic and glass can offer exceptional optics however and when you figure in the safety factor plastic comes out ahead.
When it comes to costs you don’t have to spend $200-$300 for a pair of Maui Jims in order to get a good pair of sunglasses with quality optics. These brands often have a tremendous amount of price mark up and the optics and polarization are pretty much the same in a much less expensive pair of Gargoyles or Coyote Sunglasses. The law of diminishing returns often applies to the price of sunglasses.
And finally, remember that after your bow and arrow, your polarized sunglasses are the next most important piece of gear when it comes to daytime bowfishing, so choose with care.