Sigma Water Repellent (WR) Ceramic Protector Filters (Available here) feature a new Clear Glass Ceramic shock- and scratch-resistant material with enhanced protective qualities that are 10X stronger and 30% lighter than conventional glass filters
These Clear Glass Ceramic filters are made with a special heat treatment that evenly precipitates microcrystalline spinel throughout the materials, the Clear Glass Ceramic is 10 times stronger than a conventional protective filter and three times the strength of a chemically strengthened filter.
The lens protector also contains WR coating, which repels water, dust and oil, and allows fingerprints to be easily removed. This enhanced protection helps to preserve the lens and ensure long-term, top-notch image quality.
Key features of Sigma WR Ceramic Protector Filters include:
• Scratch-resistant – Sigma’s Clear Glass Ceramic offers a Vickers hardness number of 700HV. The strength of the Clear Glass Ceramic is much stronger than chemically strengthen glass and is; 10 times stronger than conventional filters
• Thinner and lighter – This new protector is up to 50 percent thinner and is up to 30% lighter than previous Sigma filters. Clear glass ceramic is a highly durable substrate that has a greater hardness than chemically-strengthened glass and more flexibility than sapphire crystal glass.
• Rather than only the surface structure being hardened, clear glass ceramic involves a heat treatment process that precipitates microcrystals 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.
• High transmittance – Sigma’s Clear Glass Ceramic offers very high transmittance, making it ideal for use as optical glass
• 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%.
• Clear protection filter guards the front lens element from a variety of impacts and scratching without affecting image quality.
• The WR coating also serves as an anti-static coating, which helps to repel dust or other particles from clinging to the filter surface.
• Included hard acrylic case protects the filter when not in use and has been designed to prevent accidental opening.