I want to try long exposure. You know the kind. Old boat wreck in the foreground, misty sea, or the sun going down with that rolling fog that is the sea. 10+ second I guess. I bought cheap ND filter years ago and I think if I remember rightly they are great for use as a Frisbee. I only want to see if I get into this so I don't need filters that cost hundreds. What ND filter for 10+ seconds at a mid range price would you recommend?