Has anyone used ND filters before? I was thinking of getting one so I can use some new techniques I've not tried before, like long-shutter shots of waterfalls and so forth.

What rating is best to go for? I was thinking of a 6-stop one to start with.


...but now I've just seen this:
Quote Originally Posted by http://www.ephotozine.com/article/Using-a-Neutral-Density-filter-4871
Tip: use a polarising filter
A polarising filter offers a similar light reducing option as a Neutral Density 4x filter. Add two polarisers together and you can get an infinitely variable ND from 4x to very strong (almost black) by rotating the front one.
Your thoughts please.