Optical Precision Redefined: Sigma Unveils Redesigned WR Filter Series (CPL-21, PTC-21, and PUV-21)

KAWASAKI, Japan — In a move that signals a major update to its high-end optical accessory ecosystem, Sigma Corporation has announced a fully redesigned lineup of its Water- and Oil-Repellent (WR) filter series. Comprising the WR Circular PL Filter CPL-21, the WR Ceramic Protector PTC-21, and the WR Protector + UV PUV-21, this refreshed family introduces major structural and optical enhancements designed to meet the demands of modern high-resolution photography and cinematography.

Announced on November 5, 2026, from Sigma’s headquarters in Kawasaki, Japan, the new filter series represents a complete overhaul of the company’s optical filtration philosophy. Engineered with ultra-slim frames, advanced anti-reflective surface treatments, and highly durable protective coatings, the series spans diameters from 52mm up to 105mm. The launch aligns with Sigma’s broader brand modernization, offering creators a seamless blend of mechanical reliability and optical purity.

Executive Overview: The Evolution of Front-Element Filtration

In modern imaging, the front element of a lens is subjected to increasingly harsh environments while being tasked with resolving detail for sensors that regularly exceed 60 megapixels in the stills market and 8K to 12K resolutions in cinema. A poorly designed filter can introduce chromatic aberration, ghosting, flare, and severe vignetting—effectively bottlenecking the performance of premium glass.

Recognizing these challenges, Sigma’s redesigned WR series focuses on three core pillars:

1. Mechanical Optimization: Re-engineering filter frames to be significantly slimmer, particularly in large diameters, to eliminate mechanical vignetting on ultra-wide-angle lenses.
2. Surface Chemistry: Applying advanced water- and oil-repellent (WR) coatings that reduce cleaning friction and resist environmental contaminants on active sets.
3. Optical Integrity: Introducing refined anti-reflective coatings and high-transmission substrates that minimize internal reflections and preserve the Modulation Transfer Function (MTF) of the host lens.

By partnering with professional retailers like FilmTools for immediate distribution, Sigma is positioning these filters not merely as protective accessories, but as critical components of the optical path for cinematographers and landscape photographers alike.

Detailed Chronology: Developing the Next-Generation Filter Series

The development of the CPL-21, PTC-21, and PUV-21 series is the culmination of multi-year engineering efforts following Sigma’s landmark 2025 brand refresh.

[2025 Brand Refresh] 
       │
       ▼
[Identifying Optical Bottlenecks in Ultra-Wide & Cinema Lenses]
       │
       ▼
[Engineering Slim-Profile Threads & Advanced Anti-Reflective Coatings]
       │
       ▼
[Nov 5, 2026: Official Global Launch of CPL-21, PTC-21, and PUV-21]

Historically, photographers had to choose between robust protection and physical compatibility. Thicker filter profiles provided durable frames but caused dark corners (vignetting) when mounted on wide-angle optics. Conversely, thin-profile filters often sacrificed front thread depth, making it impossible to securely attach standard lens caps or stack secondary filters.

Sigma’s engineering team in Kawasaki addressed this compromise by developing a specialized manufacturing process for the aluminum and ceramic-glass components. Throughout late 2025 and early 2026, prototypes were rigorously tested on wide-angle lenses like the Sigma 14-24mm F2.8 DG DN Art and various large-format cinema primes. The resulting design achieves a profile reduction of up to several millimeters on the largest diameters (95mm and 105mm) while maintaining deep, precisely cut front threads that guarantee a secure, slip-free grip for standard clip-on lens caps.

Supporting Context & Technical Metrics

To understand the value proposition of the redesigned series, it is essential to examine the specific technical attributes and target use cases of each of the three product families.

                      ┌──────────────────────────────┐
                      │  Sigma Redesigned WR Series   │
                      └──────────────┬───────────────┘
                                     │
         ┌───────────────────────────┼───────────────────────────┐
         ▼                           ▼                           ▼
┌──────────────────┐        ┌──────────────────┐        ┌──────────────────┐
│      CPL-21      │        │      PTC-21      │        │      PUV-21      │
│Circular Polarizer│        │Ceramic Protector │        │  Protector + UV  │
│  (52mm - 105mm)  │        │  (67mm - 105mm)  │        │ (95mm & 105mm)   │
└──────────────────┘        └──────────────────┘        └──────────────────┘

1. Sigma WR Circular PL Filter CPL-21

The CPL-21 circular polarizer is designed to control polarized light, allowing users to systematically eliminate glare, suppress reflections from non-metallic surfaces (such as water and glass), and dramatically boost color saturation in landscape environments.

• Size Range: 52mm, 55mm, 58mm, 62mm, 67mm, 72mm, 77mm, 82mm, 95mm, and 105mm.
• Key Innovation: The integration of Sigma’s signature WR coating on both sides of the polarizing film sandwich. This formulation prevents water droplets from clinging to the glass—causing them to bead up and roll off—while allowing facial oils and fingerprints to be wiped away without leaving smudges.
• Primary Use Cases: Landscape photography, architectural photography through glass facades, and automotive cinematography where managing reflections on metal and windshields is critical.

2. Sigma WR Ceramic Protector PTC-21

For environments where physical impact is a constant hazard, the PTC-21 offers a specialized clear glass-ceramic substrate. Unlike standard soda-lime or even tempered borosilicate glass, glass-ceramics contain micro-crystals of spinel or lithium silicate, yielding exceptional fracture toughness.

• Size Range: 67mm, 72mm, 77mm, 82mm, 95mm, and 105mm.
• Key Innovation: High impact resistance paired with an ultra-slim frame design. The physical strength of the glass-ceramic material allows the filter element to be thinner and lighter than traditional protective filters without sacrificing impact absorption.
• Primary Use Cases: Action sports photography, rental house inventories, remote location cinematography, and shooting in high-wind environments prone to airborne gravel or debris.

3. Sigma WR Protector + UV PUV-21

The PUV-21 serves as a dual-purpose optical component, providing high-efficiency ultraviolet (UV) attenuation alongside physical element protection.

• Size Range: 95mm and 105mm (optimized for massive front-element cinema primes and large-aperture telephotos).
• Key Innovation: A focused launch in only the largest diameters, directly targeting the high-end cine and professional telephoto market. The UV absorption layer eliminates the blue/cool cast often caused by atmospheric haze at high altitudes or near large bodies of water.
• Primary Use Cases: Aerial cinematography, high-altitude landscape shooting, and general-purpose protection for expensive large-format cinema lenses.

Technical Specifications & Pricing Structure

The redesigned series is segmented by size and complexity, with pricing reflecting the premium materials used in the ceramic and large-diameter variants. Below is a comprehensive breakdown of the pricing and availability, distributed via authorized retail channels including FilmTools:

Official Industry Alignment & Design Strategy

The aesthetic and mechanical overhaul of the WR series is a direct extension of Sigma’s unified visual identity. Following the 2025 brand refresh, Sigma has systematically updated its packaging, typography, and product finishes to match the minimalist, high-precision aesthetic of its Contemporary, Art, and Sports lens lines.

The physical housing of the CPL-21, PTC-21, and PUV-21 filters features a matte black, anti-reflective anodized aluminum finish. This finish is designed to absorb stray light rather than bounce it back into the lens barrel. Internal reflections—often a major source of contrast loss when using digital sensors with reflective sensor glass—have been significantly curtailed through redesigned frame interior geometries.

Furthermore, Sigma has rigorously verified compatibility across its extensive line of interchangeable lenses. By testing the filters on extreme focal lengths (such as ultra-wide prime and zoom lenses), Sigma guarantees that even when stacked with a native lens hood or cap, the slim profile of the frame prevents light obstruction at the corners of the frame.

Future Outlook: The Role of Advanced Filters in High-Resolution Imaging

As camera manufacturers push past the 100-megapixel barrier for medium format and 60-plus megapixels for full-frame systems, the optical quality of every element in the imaging chain is scrutinized. Historically viewed by some purists as a compromise to image quality, front filters are undergoing a technological renaissance.

Sigma’s investment in specialized glass-ceramics (PTC-21) and advanced water-repellent coatings demonstrates that the accessory market must evolve alongside camera sensors. In the cinema world, where large-format sensors (such as those found in the ARRI Alexa 35, RED V-Raptor, and Sony Venice 2) demand pristine optical performance, the demand for large 95mm and 105mm filters is at an all-time high.

By focusing the PUV-21 on these ultra-large diameters and optimizing the physical profile of the CPL-21 and PTC-21, Sigma is positioning itself as a primary supplier for high-end film sets and demanding commercial shoots. The move also signals a growing trend where optical manufacturers design their accessories in strict parallel with their premier lens lines, ensuring that the physical, mechanical, and optical tolerances of the filter match the lens perfectly.

For image-makers worldwide, this redesigned WR series represents a critical upgrade path—ensuring that the front glass of their most valuable lenses is protected, reflections are masterfully controlled, and image resolution remains uncompromised under the most demanding environmental conditions.

For more information on the redesigned WR filter series, international availability, and local distributor networks, visit Sigma’s Official Global Portal. For continued coverage of optical innovations and production gear news, explore the ProVideo Coalition News Section.