K&F Concept Nano-X 3-in-1 Variable ND2–ND32, CPL and Black Mist 1/4 Filter, 37 mm

Nano-X 3-in-1 Variable ND2–ND32, CPL and Black Mist 1/4 Filter 37 mm, changes the amount of light steplessly as you turn it. It is a favourite for filming on bright days, as it lets you keep a cinematic shutter and a wide aperture without blown highlights or swapping filters between takes.

• 28 anti-reflective layers
• Screws onto a lens with a 37 mm thread.
• Water-, grease- and scratch-resistant surface

Variable ND filter

A variable ND replaces a whole set of fixed grey filters — turning the front ring changes how much light gets through, steplessly. While filming the shutter stays at 1/50 s even as the sun goes behind a cloud and comes back, with no need to stop the take or swap a filter.

Tough surface

The surface repels water and grease, so drops run off and fingerprints wipe away without smears; the coating also stands up to cleaning in the field.

One piece of glass does the work of three filters: it cuts one to five stops, kills reflections like a polariser when turned, and diffuses highlights like a Black Diffusion 1/4. The front frame is one size larger than the thread so that even a wide-angle lens shows no dark corners. A lens hood therefore cannot be fitted over the filter.