It's all about stops.
What shutter speed should I use when I'm using an ND filter? Let's say I'm using apature priority set f/16, iso 100 with no filter. Assume the the camera provides a shutter speed of 1/400s. What shutter speed should I use when I screw on my 10 stop ND filter?
*** I added
Change your camera to Manual. Set your apature and iso to the same you used for for your previous shot (f/16 iso 100 shutter speed 1/400s) Screw on your 10 stop ND filter.
Now lower your shutter speed 10 stops.
*** End add
On my camera 3 clicks on my thumb wheel = 1 stop. So I figure 30 clicks = 10 stops and this should provide a good first approximate for exposure
