World’s First Clear Glass Ceramic Protective Lens Filters

by Photo Life

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Press release by Gentec International

Sigma Canada has introduced a new series to the WR (Water Repellent) line of glass filters, the Sigma WR Ceramic Protector. Interchangeable lenses are the most important element of photographic expression, and, to the photographer, they are a valuable personal asset. To help photographers maintain the lens systems in which they have invested their time, knowledge and budgets, Sigma has developed original lens filters that meet the company’s high standards of excellence. In developing its new protective lens filter, Sigma has leveraged an unprecedented cooperative relationship with a glass manufacturer, resulting in a completely new type of glass called Clear Glass Ceramic. Featuring this advanced material, the Sigma WR Ceramic Protector is a highly reliable filter with outstanding protective capability.

With many applications in aerospace and other industries, glass ceramic is an extremely tough type of crystallized glass that serves as the foundation for Clear Glass Ceramic. While featuring the high transmittance required of optical devices, this advanced new material combines greater hardness than chemically strengthened glass and greater flexibility than sapphire crystal glass. These qualities make Clear Glass Ceramic the ideal material for protective lens filters.


  • Scratch-resistant: Clear Glass Ceramic offers a Vickers hardness number of 700HV. This is a level of hardness much higher than that of chemically strengthened glass, which is used in conventional high-strength protective filters. Moreover, this higher level of hardness helps prevent scratches and chips, which can lead to breakage of the filter.
  • 10 times stronger than the conventional filter: Made with a special process that evenly precipitates microcrystalline spinel throughout the material, Clear Glass Ceramic offers a Vickers hardness number of 700HV. The new Sigma filter made with Clear Glass Ceramic offers over 10 times the strength of a conventional protective filter and over 3 times the strength of a high-strength protective filter made with chemically hardened glass of the same thickness.
  • Thinner and lighter: Since Clear Glass Ceramic is extremely strong, the Sigma WR Ceramic Protector is up to 50 percent thinner and weighs up to 30 percent less than previous Sigma filters while offering a higher level of strength.
  • High Transmittance: Sigma’s Clear Glass Ceramic offers very high transmittance, making it ideal for use as optical glass.
  • Water-repellent coating: The WR coating reflects only 0.24 percent of visible light, thereby minimizing flare and ghosting. Its ability to repel both water and oil is also excellent: water drops bounce right off, and fingerprints are easily removed with a quick wipe. This coating also offers high lubricating ability, giving it more than ten times the scratch-preventing capability of Sigma’s current Super Multi-Layer Coating. The coating’s antistatic function helps prevent static electricity from attracting dust and other particles, which can easily be blown off the filter when they do adhere.

Sigma is distributed in Canada by Gentec International.
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