Calculating exposure times using the NiSi Filters app
ND-Filter Expert App - The Best ND-Calculator in the whole Universe
PolarPro app icon on Apple iPhone screen. A photo and video tool to calculate which ND filter for a desired shutter speed. App now discontinued Stock Photo - Alamy
ND Filter Expert - Apps on Google Play
How To Shoot Long Exposures Without ND-Filters - Sony Smooth Reflectio
ND-Filter-Belichtungszeit mit der ND Filter Expert App berechnen - digitalkamera.de - Fototipp
ND Filter Calc (DSLR) - Apps on Google Play
Kenko Global - Shoot professional photos with ND filters