Sigma

Sigma AFK9B0 105mm WR UV Filter

Name: Sigma AFK9B0 105mm WR UV Filter
Brand: Sigma
SKU: AFK9B0

★★★★★4.8 (165 reviews)

Protect every millimeter of your 105mm glass — weather-resistant UV filtration built for serious field work.

$274.00*

*Price sourced from Amazon.com. Last updated:Jul 14, 2026.Price and availability are subject to change.

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Overview

A 105mm lens is typically one of the most specialized and optically refined pieces of glass in a photographer's kit — whether that's a macro lens built for razor-thin depth of field, or a portrait lens prized for its compression and smooth rendering. Putting a subpar filter in front of that glass is a false economy. The Sigma 105mm WR UV Filter is built to sit invisibly in the optical path — it contributes no color shift, no softening, no flare artifacts — while providing meaningful protection against the front element damage that can sideline an expensive lens. For outdoor macro shooters working close to subjects in wet grass or garden environments, and portrait photographers shooting on-location in variable weather, having a reliable protective filter changes how confidently you can work.

The physical filter is well-made in the ways that matter on a real shoot. The metal ring threads cleanly and consistently, holding securely without binding — important when you're swapping filters or attaching a lens hood in the field. The water-repellent coating on the glass is a practical upgrade over uncoated filters: in light rain or coastal mist, the surface sheds moisture quickly and wipes clean without the streaking that can ruin a sequence of shots. At 105mm, this is a premium accessory for a premium lens — and the construction reflects that positioning appropriately.

Key Features

New Concept Filters that suit the high optical performance

Weather Resistant

Specifications

Filter Size

105mm

Filter Type

Coating

Water-Repellent (WR)

Brand

Sigma

Model

AFK9B0

Pros & Cons

👍 Pros

Large 105mm diameter means it protects the full front element of telephoto and macro lenses that are expensive and difficult to service.
Water-repellent coating keeps the filter surface clean and clear during outdoor portrait or wildlife sessions in variable weather.
Optical quality matched to high-performance lenses — no resolution loss or color fringing added to already-demanding optical systems.
Solid metal ring construction handles the physical stress of frequent mounting without developing slop in the threads.
Neutral UV filtration provides protection from ultraviolet haze in outdoor environments without warming or cooling the image.

👎 Cons

105mm is a large, specialized filter size — it won't cross over to other lenses in most kits, limiting its versatility as a single purchase.
The larger diameter and quality coating make this filter more expensive than budget 105mm alternatives, which may feel steep for a purely protective accessory.
No carrying case or storage pouch included — a filter this size benefits from dedicated storage to avoid scratching.
Weather resistance covers the glass surface only; the ring-to-lens interface is not independently gasketed or sealed.

Frequently Asked Questions

Does a UV filter at 105mm affect bokeh or background rendering on a macro or portrait lens?

No — a quality UV filter like this one introduces no measurable change to out-of-focus rendering. The glass is optically neutral, so the smooth bokeh you expect from a 105mm portrait or macro lens is fully preserved. You're adding protection without altering the character of the lens.

The 105mm filter size is fairly specialized — will this fit lenses other than Sigma's 105mm?

Yes — any lens with a 105mm filter thread will accept it, regardless of manufacturer. That said, 105mm is a large and less common thread size, so check your specific lens's front thread diameter before purchasing.

How does the water-repellent coating on this filter actually perform in wet conditions?

The WR coating causes water to bead and roll off the glass surface rather than spreading into a smear — in light rain or mist, a quick wipe clears the filter cleanly without streaking. It won't keep water entirely off the surface, but it dramatically speeds up the recovery time between shots in wet conditions.

Is this filter thick enough to cause vignetting on wide-angle lenses?

At 105mm this is almost exclusively used on telephoto, portrait, or macro lenses — focal lengths where vignetting from a filter ring is essentially never an issue. This is not a concern in practice for the lenses this filter size is designed for.

Can I stack another filter on top of this UV filter?

Yes, the front thread remains accessible for stacking, but Sigma doesn't rate or recommend specific stacking combinations. Each additional filter layer introduces a marginal risk of vignetting or optical degradation, so stacking should be done thoughtfully.