How many stops for a ND filter?

I am driving to Alaska in May with my hubby for a 3 month visit, and I need a neutral density filter to block light on water & fog images. Should I purchase an ND 1.8 (6stops) or a ND 3.0 (10 stops)?

Will it be okay to buy a filter that will fit my largest lens, and purchase a step-down ring so that I can use it on my smaller lenses? Any problems with this option?

Any other suggestions regarding the ND filter that anyone would like to pass along?

Thanks in advance,
Dottie

I assume you're talking about split or graduated neutral density filters? If so, the strongest I use is a 5-stop, and I get more use out of 1-, 2-, and 3-stop versions. I can't see where a regular screw-in ND would help with fog or water. I've got a 1.8 that I use to drop shutter speeds in bright light so I can blur moving water, but that's a pretty narrow application for me.

BTW- Three months is about right for a first visit to Alaska! Folks who come up for a week or two soon discover the facts of life: The distance from one side of the state to the other is comparable to the span between Seattle and Miami, or Seattle and Mexico City. And there are darned few roads. More time translates into more opportunity to reach remote spots between. Well done!

I recommend the Singh Ray Vari n Duo. It blocks up to 8 steps, but can be adjusetd for fewer stops and is combine with a polarizer, which is great for reducing glare on wet rocks. It is pricey, but IMHO its worth it! http://www.singh-ray.com/varinduo.html I am not on Singh Ray's payroll. I wish I were:)

If it is too expensive, six stops usually covers my needs, allowing me to make fantastic waterfall images.

I use two P-holder ND filters, a .9 and a 1.2. Together or separately they give me 3 stops, 4 stops, or 7 stops. I also can combine them with GND filters and or polarizer.

I'm interested in the Singh Ray variable ND filter but I've never used one or even seen one and it's price is off-putting.

I use a 3 stop GND and find that it works well for typical lighting up here. I agree with Hank. You're taking enough time to get a good look around. People who blast through in a week barely get a teaser of what AK has to offer.

For most uses a 3 stop gradient and a 3 stop hard edge combined with a circular polarizer will do it. Whatever you do, don't do auto exposure, calculate your needed exposure and then manually set the exposure. The fool auto exposure will wreck all your filter plans.

Lynn