Interchangeable lenses are essential elements of photographic expression and are valuable components of a photographer's equipment. SIGMA has developed innovative filters for lens front lenses that meet high-quality standards and help photographers protect their investments of time, experience, and money. In creating the new protective filter, SIGMA collaborated with a glass manufacturer to produce a new type of clear glass ceramic. The SIGMA WR Ceramic Protector, made from this advanced material, is an extremely reliable filter that offers excellent protection.

Glass ceramic is a highly resistant, crystallized glass widely used in aerospace and other industries. This advanced material combines greater hardness than chemically hardened glass with greater flexibility than sapphire crystal glass, while also providing the high light transmission required for optical devices. These properties make clear glass ceramic the ideal material for lens protection filters.

Conventional high-strength protective filters use chemically hardened glass, which is only hardened on the surface through chemical processes. In contrast, clear glass ceramics undergo a special heat treatment that ensures an even distribution of the mineral spinel, giving the entire filter consistent hardness. Clear glass ceramic is ideal for protective filters due to its superior hardness compared to chemically hardened glass and its greater flexibility compared to sapphire crystal glass. Additionally, clear glass ceramics are resistant to breakage from small scratches or chipping, reducing the risk of fragmentation into small pieces and offering a higher degree of security.