A few of you may recognize the following shot. I shared it in the POTD thread in August I believe after a trip to the Great Smoky Mountains National Park in Tennessee. I had to stop my lens down all the way to f/22 to get a slow enough shutter speed to get the look I was after. We are heading back to the mountains in about a week and this time I want to be more prepared so I am planning on getting an ND filter. I don't want to spend a ton of money on this as it's something I won't use all that often, so I've pretty much decided on the Cokin P series. I'm going to start off with just an ND for now and then probably pick up some GND down the road. Now, for the question. What strength of ND should I go with? B&H has 1, 2, and 3 stop variants available. I am leaning toward the 3 stop to get the most effect possible. I figure I can always bump up the ISO to get back a couple stops, but if the ND isn't dark enough, there is nothing I can do to drop stops, short of stopping down the aperture to dangerous levels. Any advice? Thanks.