At f / 5.6 to f / 8 you in the bright sunshine more than 1 / 1000s shutter speed, comes with the filter so perfectly to 1 / 50s zoom. Will it be sunny and I'm still well down on human ISO values (to about 400). Say: Who does not tons of money in a variable ND filter (quasi a double pole filter) wants to spend, can find a very good companion to the movies.
For bulb exposures can use it conditionally. It must not be too sunny, then it works. Who wants to blur, for example a stream and operates in the dense forest, the lucky. With ISO 100 and perhaps Aperture f / 11 you get out very respectable results. Who wants to do that during the day, had better access equal to a 1000x filter.
Conclusion: The issue of quality I've saved me once. There is a filter from the 'Hoya Pro1 digital' series, of course, the quality is top. For films or for long exposures with slightly less light (forest, cloudy, twilight) the ideal neutral density filter, but still too weak for use on the day.