Sigma WR Ceramic Protector

Sigma developed innovative filters for lens front elements that meet the company's high quality standards and help photographers utilize the lenses they have invested significant time, experience, and money into for years. In developing the new protective filter for lens front elements, Sigma collaborated with a glass manufacturer for the first time to create a new type of glass, clear glass-ceramic.

Glass-ceramic is an extremely resilient, crystallized glass that serves as the basis for clear glass-ceramic and is widely used in aerospace and other industries. This advanced new material combines greater hardness than chemically tempered glass with higher flexibility than sapphire crystal glass, while also possessing the high light transmittance required for optical devices. These properties make clear glass-ceramic the ideal material for lens protection filters.

The chemically tempered glass used for conventional high-strength protection filters is only hardened on the surface through chemical processes. In contrast, clear glass-ceramic is produced using a special heat treatment that ensures uniform filling with the mineral spinel, providing the entire filter with consistent hardness. Clear glass-ceramic is the ideal material for protection filters due to its combination of greater hardness than chemically tempered glass and higher flexibility than sapphire crystal glass. It is also shatter-resistant, even in the event of small scratches or chips. With the reduced risk of shattering into small fragments, it offers a higher level of safety.