Neutral Density Variable Filter K&F 49mm ND2–ND400 adjustable gray (KF01.1398)

The Neutral Density Variable Filter K&F 49mm ND2–ND400 adjustable gray (KF01.1398) is a 49 mm variable ND filter that provides continuous light reduction from approximately 1 stop (ND2) up to 9 stops (ND400). It is designed to allow precise control of exposure, enabling longer shutter speeds, wider apertures in bright conditions, and improved motion blur control for both still photography and video. The slim 49 mm mount fits lenses with matching filter threads and permits gradual adjustment of density without changing filters.

Advantages

This K&F variable ND filter offers smooth transition between densities for accurate exposure control and simplified operation compared with switching multiple fixed ND filters. Its compact 49 mm size reduces vignetting risk on small- and medium-format lenses and keeps the front profile slim for easier handling. The adjustable mechanism enables incremental light reduction which is useful when fine-tuning shutter speed or depth of field while shooting in variable lighting. Constructed for general photographic use, it supports prolonged exposures and controlled motion effects without altering color balance when used correctly.

Suitable for

• Landscape photography requiring long exposures to smooth water or clouds
• Long-exposure urban photography to blur traffic and create motion trails
• Video recording where consistent light reduction and aperture control are needed
• Portraits shot in bright daylight when using wide apertures for shallow depth of field

Key specifications

• Thread diameter: 49 mm
• Density range: ND2 to ND400 (approx. 1 to 9 stops)
• Type: Variable neutral density (adjustable)
• Effect: Continuous light reduction for extended exposures and aperture control
• Optical construction: Multi-element coated glass designed to reduce reflections
• Mount profile: Slim design to minimize vignetting on compatible lenses

How to use

Attach the filter to a lens with a 49 mm front thread by screwing it on until secure; avoid overtightening. Rotate the front ring to adjust the density gradually until the desired exposure or motion effect is achieved. When using long exposures, stabilize the camera on a tripod and use a remote shutter release or timer to prevent camera shake. For video, monitor exposure and histogram while rotating the filter slowly to maintain consistent brightness. Be aware of potential cross-polarization or X-patterns at extreme settings and reduce density if such artifacts appear.

Usage recommendations

For best results, combine the variable ND filter with careful exposure metering and manual camera settings. If using the filter at or near maximum density, check images for uneven darkening (X-pattern) and stop down or reduce rotation if necessary. Use lens hoods or shading to minimize stray light and preserve contrast during long exposures.