B+W 1101638 112mm Master HTC Kaesemann C-POL Filter

The B+W 112mm Master HTC Kaesemann Circular Polarizer is a large-format filter built for photographers running front-heavy glass — 400mm f/2.8 primes, large-diameter standard zooms, or specialty wide-angle lenses with 112mm filter threads. The Kaesemann manufacturing process distinguishes this from commodity CPL filters: the polarizing film is tensioned and cemented between two optical glass elements rather than simply sandwiched, which maintains consistent polarization performance across the entire filter diameter and eliminates the color fringing and uneven effect that cheaper constructions produce at the edges of large-format glass. The High Transmission formulation is the practical upgrade — at approximately 1 stop of light loss versus the 1.5–2 stops typical of standard CPL designs, it preserves autofocus tracking performance and shutter speed headroom that matters most when the filter lives permanently on a fast telephoto or a large ultra-wide.

In the field, the MRC Nano coating is the feature that earns the most appreciation after extended use. The hydrophobic nano-layer keeps the filter surface clean between shots in the conditions where CPLs see the most use — coastal landscapes with salt spray, overcast rain days shooting architecture, forest environments where moisture accumulates quickly. The thin-profile mount keeps vignetting in check down to 17mm on full-frame, and the black knurled ring gives reliable rotation grip for dialing in polarization effect on scenes where the optimal angle changes quickly. The included QR code for authenticity verification is a meaningful addition at this price point — counterfeit B+W filters are not hypothetical, and knowing the filter glass matches the optical specification is not a trivial assurance when the filter is doing precision work in front of a lens worth multiples of the filter's cost.