It’s taken me 20+ years to figure out that for long-exposure work, having a set of ND filters that are 2 stops apart is the best way forward.

I have always used 1, 2, 3, 6 and 10 stop ND filters. But over the past while I have found that the jump between 3 stops to 6 stops is far too much. Same for the leap between 6 stops and 10.

So now I use 2, 4, 6, 8 and 10 stop ND filters.

Further to this, what I should let you know is that for the past decade, I work my exposures out in 1 stop increments. I do not meter in 1/2 stops or 1/3rd stops. They are in my view - simply too fine and 1 stop differences is as fine a granularity that I need for my films.

I would like to also add that it becomes a lot easier to meter, and to add exposure compensation when adding ND filters, if you work with your camera set to meter at 1-stop increments only.

Consider if your camera is set to expose at 1/3rd stop increments. It is very hard to work out for 2 stops more would be if your exposure is at 1/9th of a second. It becomes a lot easier if your camera rounds it down to 1/8th of a second. Adding two stops onto this means you just divide it by 2, twice:

1 stop increment = 1/4 of a second

2nd stop increment = 1/2 of a second.

I like working in 1 stop differences. It’s as fine as I need it, and it also simplifies my working out the exposure compensation difference when applying ND filters.