ND filters and focus
How
N
eutral
D
ensity filters relate to focus reduction.
ND =
Density
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2.0
3.0
4.0
Reduction
by
f
-stops
1/3
2/3
1
1 1/3
1 2/3
2
2 1/3
2 2/3
3
3 1/3
6 2/3
10
13 1/3