Interchangeable lenses are the most important elements of photographic expression and are part of the photographer's valuable personal equipment. We have developed innovative filters for lens front elements that meet the company's high quality standards and help photographers get years of use out of the lenses in which they have invested so much time, experience and money. When developing the new protective filter for lens front elements, we used the cooperation with a glass manufacturer for the first time to create a new type of glass, clear glass ceramic. The SIGMA WR CERAMIC PROTECTOR made of this advanced material is an extremely reliable filter with outstanding protective function.
Glass-ceramic is an extremely resistant 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 and greater flexibility than sapphire crystal glass, and has the high light transmission required for optical devices. These properties make clear glass-ceramic the ideal material for protective Lens filters.
Highly impact-resistant clear glass-ceramic
The chemically hardened glass used for conventional high-strength protective filters is only hardened on the surface by chemical processes. In contrast, clear glass-ceramic is produced with a special heat treatment that ensures an even filling with the mineral spinel, giving the entire filter a continuous hardness. Clear glass-ceramic is the ideal material for protective filters due to its combination of greater hardness than chemically tempered glass and greater flexibility than sapphire crystal glass. Clear glass-ceramic is also resistant to breakage if small scratches or chips occur. As the risk of shattering into small fragments is reduced, it offers a higher level of safety.
Scratch resistance
Clear glass ceramic has a Vickers hardness of 700 HV.* This hardness is significantly higher than that of chemically tempered glass used for conventional high-strength protective filters. In addition, this greater hardness prevents scratches and splinters that can cause the filter to break.
*In the Vickers hardness test, a diamond instrument is pressed onto a material and the depth of the impression is used to calculate the hardness of the material, which is given as a Vickers pyramid number (HV).
10 times harder than a conventional protective filter, 3 times harder than a chemically hardened glass filter
With clear glass-ceramic, a special process ensures uniform filling with the microcrystalline spinel. It thus achieves a Vickers hardness of 700 HV. The new SIGMA filter made of clear glass ceramic is 10 times harder than a conventional protective filter and more than 3 times harder than a high-strength protective filter made of chemically hardened glass of the same thickness.
Thinner and lighter overall thanks to the advanced new material
Because clear glass-ceramic is extremely hard, the SIGMA WR CERAMIC PROTECTOR is up to 50 percent thinner and weighs up to 30 percent less than previous SIGMA filters, yet has greater hardness.
High light transmission
SIGMA's clear glass ceramic offers very high light transmission - the ideal optical glass.
High quality
The SIGMA WR CERAMIC PROTECTOR is compatible with almost all of our Lens models. The protective filter allows light to pass through evenly from the center to the edges of the image. All SIGMA Lens in the new product lines have been tested with SIGMA's proprietary Modulation Transfer Function (MTF) measurement system (A1)* using 46 megapixel Foveon direct image sensors. The design of the SIGMA WR CERAMIC PROTECTOR also meets this demanding standard.
*A1: Aizu1
Using a newly developed advanced material from glass manufacturer Ohara Inc.
The SIGMA WR CERAMIC PROTECTOR is made of a new advanced material, clear glass ceramic, using a newly developed crystallized glass from glass manufacturer Ohara Inc.
Water-repellent coating (WR)
The WR coating reflects only 0.24 percent of visible light, minimizing stray light and ghosting. The water and oil repellent properties are also excellent: water droplets bounce off and fingerprints can simply be wiped off quickly. This coating also has high gliding properties and is ten times more scratch-resistant than the current super multi-layer coating. The antistatic properties of the coating prevent the static adhesion of dust and other particles. These can easily be blown away by the filter.
