K&F Filter Kit 4-in-1 (Nano-K) 40.5 mm — UV, CPL, ND4, Protective

The K&F Filter Kit 4-in-1 (Nano-K) 40.5 mm includes four screw-in filters sized for lenses with a 40.5 mm filter thread: a UV filter, a circular polarizer (CPL), an ND4 neutral density filter and a clear protective filter. These filters are designed to reduce surface ultraviolet haze, cut reflections and glare, control light entering the lens for longer exposures, and shield the front element from dust, moisture and minor impacts. The Nano-K coating improves optical transmission and helps resist fingerprints and smudges while maintaining color neutrality for general photography and outdoor shooting.

Advantages

The kit offers broad practical coverage in a compact set: UV filtration for reducing atmospheric haze and protecting the front element, a CPL for managing reflections and increasing color saturation, an ND4 for reducing exposure by two stops to enable slower shutter speeds or wider apertures, and a protective clear filter for everyday lens protection. Each filter is screw-mounted for secure attachment and straightforward use. Nano-K surface treatments improve cleaning and reduce ghosting and flare without introducing visible color cast.

Suitable for

• Landscape and travel photography where haze reduction and polarity control are needed
• Outdoor portrait and product shots requiring reduced reflections and richer colors
• Long-exposure daytime photography using ND4 to slow shutter speeds
• Everyday lens protection during transport and fieldwork

Key specifications

• Filter thread size: 40.5 mm
• Included filters: UV, Circular Polarizer (CPL), ND4 (2-stop neutral density), Protective/Clear
• Coating: Nano-K anti-reflective and easy-clean coating
• Mount type: screw-in metal or alloy ring (low-profile)
• Optical effect: ultraviolet reduction, polarization for glare control, 2-stop light reduction, front-element protection

How to use

Screw the appropriate filter onto the front of a lens with a 40.5 mm filter thread. Use the UV filter by default to reduce haze and provide continuous front-element protection. Rotate the CPL while viewing through the viewfinder or live view to find the angle that reduces reflections and increases color saturation; fine adjustment is possible by turning the outer ring of the CPL. Attach the ND4 when you need to reduce exposure by approximately two stops for motion blur or wider-aperture effects in brighter conditions. Remove filters or swap them as shooting conditions change; always store filters in their protective case when not in use to avoid scratches.

Usage recommendations

For best results, keep threads clean and avoid overtightening. When using the CPL with wide-angle lenses, check for uneven polarization across the frame. Combine the ND4 with a tripod for stable long-exposure shots and use lens hood where possible to reduce stray light. Clean the Nano-K coated surfaces with a blower, microfiber cloth and approved lens cleaner to maintain optical performance.