K&F Concept Nano-X Pro variable ND filter ND2–ND32 77 mm, brass frame

Nano-X Pro — variable ND filter 77 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.

• 36 anti-reflective layers, reflectance 0.15 %
• Screws onto a lens with a 77 mm thread.
• The surface repels water and grease and resists scratches

Light under control with one turn

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.

The glass carries 36 anti-reflective layers and reflects only 0.15 % of the light, so no ghosting or veiling appears against the light. 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.

The ring has hard stops at ND2 and ND32, so the filter cannot be turned into the position where variable NDs produce a dark cross over the image. The one-to-five-stop reduction is set with a lever on the rim, so it can be changed with an eye at the viewfinder. The frame is brass, not aluminium. Brass does not seize in the thread, so the filter comes off even after a season on the lens and does not jam at the moment it has to be swapped in a hurry.