Variable ND (VND)
Variabele ND (VND) · Lens & optics
An ND filter with a rotating ring that varies the strength steplessly, built from two polarised layers.
Useful for video and run-and-gun work: one filter replaces a whole set. Typical range is ND2 to ND400 (1 to 8.6 stops). Downside: at maximum strength an X-shaped dark cross appears as the polarising layers cross each other. Cheaper VNDs have colour casts or vignetting. Some models (Kase, NiSi) include hard stops to avoid this. For long exposures on a tripod, a fixed ND remains optically better.
Tools that help with this: