Interchangeable lenses are crucial for photographic expression and valuable equipment for photographers. SIGMA has developed innovative filters for front lens elements that meet high-quality standards and help photographers make the most of the lenses they have invested significant time, experience, and money in over the years. In developing the new protective filter for front lens elements, SIGMA collaborated with a glass manufacturer to produce a new type of material, clear glass-ceramic. The SIGMA WR Ceramic Protector, made from this advanced material, is an extremely reliable filter with outstanding protective properties.

Glass-ceramic is a highly resistant, crystallized glass that is commonly used in aerospace and other industries. This advanced material combines greater hardness than chemically tempered glass with more flexibility than sapphire glass, while also providing the high light transmittance required for optical devices. These characteristics make clear glass-ceramic ideal for lens protection filters.

Conventional high-strength protective filters use chemically tempered glass, which is only hardened on the surface through chemical processes. In contrast, clear glass-ceramic undergoes a special heat treatment that ensures an even distribution of mineral spinel, giving the entire filter consistent hardness. The combination of greater hardness than chemically tempered glass and greater flexibility than sapphire glass makes clear glass-ceramic the perfect material for protective filters. Additionally, clear glass-ceramic is shatterproof, minimizing the risk of fragmentation into small pieces and providing a higher level of safety.