Sigma 105mm WR Clear Glass Ceramic Protector

Characterized by its uniquely durable construction, the WR Ceramic Protector Filter is a clear filter designed to guard the front of a lens from impacts, scratching, and other elements. Developed using a clear glass ceramic substrate, this filter blends a high 99.76% transmittance value with greater hardness than chemically-strengthened glass & greater flexibility than sapphire crystal glass. This results in a build that is shock & scratch-resistant to withstand a variety of impacts while shooting. Additionally, a water-repellent coating has also been applied to resist water droplets and fingerprint smudging, as well as static electricity from attracting dust or other particles. Built for use in trying conditions, the unique design of the WR Ceramic Protector Filter helps to maintain the lens' inherent image quality while affording a high degree of protection. Unique construction has a Vickers hardness number of 700HV, making it both scratch- and shock-resistant. This hardness also lessens the likelihood of scratching or chipping that can lead to the filter shattering. Rather than only the surface structure being hardened, clear glass ceramic involves a heat treatment process that precipitates micro-crystals of a mineral called spinel in order to achieve consistent, even strength across the entire filter surface. This strength also enables the design of the filter to be notably thin and lightweight. A water-repellent (WR) coating has been applied that, in addition to preventing water and oil from adhering to the filter surface, also helps to minimize ghosting and flare. This coating reflects 0.24% of light, giving an overall transmittance value of 99.76%. The WR coating also serves as an anti-static coating, which helps to repel dust or other particles from clinging to the filter surface. The included hard acrylic case protects the filter when not in use.... More