ND filter: shutter conversion
Base shutter × filter density → new shutter speed for long exposure
Input
New shutter
Within camera range
8.2 с
Compensation: 10 stops (×1024)
ND1000 (10 stops) turns 1/60 s into 16 s — water goes milky. Beyond 30 s use Bulb mode and a remote. Alternatively raise ISO or open aperture by the same stops.