How many stop ND Filter?

[AaronBBrown]

I love taking long exposure shots of the ocean like this one, taken at dusk with a 15 sec exposure (and a polarizer to cut down on some of the light):
http://www.soggydiving.com/gallery/albums/userpics/10001/img_2556_filtered.jpg

Unfortunately, the S2 only goes down to f/8, so I have to wait until it is very dark to take this type of shot. I'd like to be able to take this type of shot during the day to capture more interesting colors. I think what I need is a several-stop ND filter, but I'm not sure how many stops I would need to be able to take long exposure shots like this during the daytime, nor where to get it.

Help?

[BowerR64]

What is the long exsposure doing in that picture?

[AaronBBrown]

What is the long exsposure doing in that picture?

The 'fog' in the picture is not fog, but waves on a rough day.

[DonSchap]

I believe you acheive: one full f-stop with the NDx2 two full f-stops with the NDx4 three full f-stops with the NDx8

At least, that's what I was told when I purchased my Vivitar 500/1000mm Mirror lens. Never bothered to go back and check, though.

[AaronBBrown]

That is correct, but I am unsure of how many stops I would need. Maybe I should just try a ND8 and see what happens.

[TampaJim]

ND8 is three stops. I would buy a ND8 - you could always open the S3 back up if it is too dark.