Interchangeable lenses are essential for photographic expression and are valuable equipment for photographers. SIGMA has developed innovative filters for lens front elements that meet the company's high-quality standards, allowing photographers to utilize the lenses they have invested significant time, experience, and money in for years. In creating the new protective filter for objective front lenses, SIGMA collaborated with a glass manufacturer for the first time to produce a new type of material, clear glass ceramics. The SIGMA WR Ceramic Protector, made from this advanced material, is an extremely reliable filter with outstanding protective capabilities.

Glass-ceramic is a highly resistant, crystallized glass that serves as the foundation for clear glass ceramics and is widely used in space travel 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 ceramics the ideal choice for lens protection filters.

Conventional high-strength protective filters use chemically hardened glass that is only hardened at the surface through chemical processes. In contrast, clear glass ceramic undergoes a special heat treatment that ensures an even distribution of the mineral spinel, resulting in continuous hardness throughout the filter. The combination of greater hardness than chemically hardened glass and greater flexibility than sapphire crystal glass makes clear glass ceramic the perfect material for protective filters. Additionally, clear glass ceramic is break-resistant against small scratches or chipping, reducing the risk of fragmentation into small pieces and offering a higher degree of safety.