Neutral Density Variable Filter K&F 43mm adjustable ND2–ND400, gray (model SB7790)

The Neutral Density Variable Filter K&F 43mm adjustable ND2–ND400 is a screw-in gray filter designed to control the amount of light reaching the camera sensor. With a 43 mm thread size, this variable ND filter lets you continuously adjust light reduction from approximately 1 to 8.6 stops (ND2 to ND400), enabling longer shutter speeds and wider apertures in bright conditions without changing exposure settings or ISO. The optical glass and neutral-gray tint preserve color balance while reducing overall exposure, making the filter suitable for landscape, long-exposure, and motion blur photography with lenses that accept 43 mm filters.

Advantages

The adjustable ND2–ND400 range provides flexible control over exposure without the need to carry multiple fixed ND filters. Its screw-in 43 mm mount ensures secure attachment to compatible lenses and maintains a compact profile, avoiding added bulk compared with drop-in or filter-holder systems. The neutral gray glass is formulated to minimize color cast so that white balance adjustments remain minimal in post-processing. Continuous adjustment enables precise framing and exposure decisions on location, and the robust metal frame offers consistent alignment and rotation during use.

Suitable for

• Landscape photography requiring long exposures to smooth water and clouds
• Long-exposure cityscapes and light-trail photography
• Motion-blur effects for waterfalls, rivers, and moving subjects
• Portraits or shallow-depth-of-field work in bright daylight when a wider aperture is needed

Key specifications

• Filter type: variable neutral density (gray)
• Thread size: 43 mm screw-in
• Density range: adjustable from ND2 to ND400 (approx. 1 to 8.6 stops)
• Material: optical glass with metal mount
• Color cast: neutral gray for minimal colour shift

How to use

Screw the filter gently onto the front thread of a 43 mm lens until it sits flush but not over-tightened. Rotate the front ring to adjust the density from light reduction equivalent to ND2 up to ND400 while observing the exposure changes through the viewfinder or on the LCD. When composing long exposures, set your camera on a tripod and use live view or an exposure meter to determine the required shutter speed and aperture. Use remote release or self-timer to avoid camera shake during longer exposures. Check for any vignetting at wide focal lengths and adjust composition or remove the filter if necessary.

Usage recommendations

For best results, use the filter with a sturdy tripod and consider bracketing exposures for scenes with wide dynamic range. Clean the glass with a microfiber cloth before and after use to avoid dust and smudges. When shooting at the highest densities, monitor for cross-polarization or X-pattern artifacts and reduce density if these appear by slightly backing off the rotation.