Well, I finally got to use my new ND filters. ; This was shot with both the 0.6 and 0.9 attached to the lens. Sony DSC-H50, 8s, F2.8, ISO 200, +0, 7.9mm Focal Length
Hopefully I'm not muddying the waters here, but another kind of ND filter to think about your filter arsenal is a graduated neutral density filter. I found that light reflected off of water looses a couple of stops (or more). when getting fireworks on water, the results are colors look more saturated but washed out in the sky. With a graduated neutral density filter, part is clear, part is ND with a gradual fall off between the two. By aligning the graduation on or around the horizon, you can "turn down" the f/stops for the pyro but let the reflections come on in. It also works for almost any reflections as well. I would have had a tough(er) time with this one without the grad ND. Now, truth be told, I can also "imitate" a graduated ND filter by putting my hand over the lens roughly in the area I want to dim out, and then move my hand around during the exposure before pulling it out of the way. This works best with an exposure of more than a few seconds, and it's also easy to overdo it, but it works in a pinch. Oh, I bought Conkin grad ND filters - and wish I had held out for a better set. They are not coated and tend to reflect horribly for bright specular points of light (like fireworks). ;