Interchangeable lenses are essential for photographic expression and are valuable equipment for photographers. SIGMA has developed innovative filters for lens front lenses that meet high-quality standards, helping photographers 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 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 functions.

Glass-ceramic is a highly resistant, crystallized glass 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, along with the high light transmission required for optical devices. These properties make clear glass ceramics ideal for lens protection filters.

Conventional high-strength protective filters use chemically hardened glass, which 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, providing the entire filter with consistent hardness. 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, minimizing the risk of fragmentation into small pieces and offering a higher degree of security.