ULR 28DSMC UV Lens Protector Filter — 99.6% Transmittance, 28-Layer Coating, Schott B270 Glass

Your lens filter thread diameter is printed on the lens barrel or the inside of the lens cap, marked with a ø symbol (e.g., ø72 means you need a 72mm filter). Match that number to the size option above. Common sizes range from 37mm (≈1.5") to 82mm (≈3.2") and beyond.

A transmittance of 99.6% (±0.1%) means the filter passes nearly all visible light to your sensor, with a reflectance of ≤0.1%. In practice, this generally means no visible exposure shift, no color cast, and no ghosting or flare from internal reflections — the filter behaves as if it isn't there optically.

Schott B270 is an optical-grade crown glass manufactured in Germany, known for its high clarity, low iron content, and consistent refractive index. It is commonly used in optical instruments where color neutrality and minimal distortion are required. Using B270 glass as the substrate generally results in a more color-neutral filter compared to standard float glass.

The 28 layers of multi-coating are applied to both sides of the glass (28 layers per side, 56 total). These coatings serve multiple functions: anti-reflection (reducing reflectance to ≤0.1%), water and oil repellency on both surfaces, and light moisture resistance. The result is a filter that is easier to clean and more resistant to fingerprints, water spots, and light condensation.

The frame thickness is 3.3mm (≈0.13"), which is relatively slim for a UV protector. In most cases, vignetting is not visible at standard focal lengths. On ultra-wide lenses (typically below 16mm full-frame equivalent), some vignetting may appear at the widest apertures — this is generally true of any filter at those focal lengths.

The frame is machined from 6061 aerospace-grade aluminum alloy, which provides a good balance of rigidity and light weight. The glass hardness is rated at 6H on the Mohs scale, making it more scratch-resistant than standard optical glass. The frame is designed to resist cross-threading and jamming during installation and removal.

Yes, the standard threaded ring allows stacking with other screw-in filters. However, stacking filters generally increases the risk of vignetting on wide-angle lenses and may introduce additional reflections. For most shooting scenarios, using this UV protector alone or swapping it for a CPL or ND when needed is the recommended approach.