What ND for dawn/dusk cloud fun?

[Nawty]

I'm looking to buy a couple of NDs to do long exposure and I know this is a bit of a 'piece of string answer' but...

I don't necessarily want super-maxed-out-long-exposure-can't-see-the-waterfall type exposures and I would like to do a bit of dawn/dusk landscapes with a bit of cloud movement, I assume a 10-stopper would be too much for this but what would be appropriate?

I've been looking at the new Hi-Tech Firecrest filters which say they are stackable so was thinking of a 3 stop and a 7 stop, would that work or would a 5 and 10 be more flexible?

Thanks

 

[a1ex2001]

If you just want a little movement I'd go for a 3 stop if your shooting stopped down at low ISO your exposure will be reasonably long anyway. I will add I'm not a fan if this effect so that might give me a bias towards the lower number of stops!

 

[Stu Meech]

A 6 is pretty useful at dawn/dusk, I also use a 3 for when I want a second or two of movement.

 

[Nawty]

Cool, thanks folks.

I'm using m43 so stopping down to f/11 and beyond is in sever diffraction territory so I would probably err towards the 6 or 7 but a 3 would be handy for shooting the primes wide open (which is virtually every time you use them) so I might get one anyway.