Often it is necessary or desirable to balance the light intensity in one part of a scene with another. This is especially true in situations where you don't have total light control, as in bright contrasty landscapes.
Exposing for the foreground will produce a washed-out, over-exposed sky while exposing for the sky will leave the foreground dark and under-exposed. Graduated Neutral Density filters are part clear, part neutral density. They allow the transition to be blended into the scene, often imperceptibly.
- Some Tiffen graduated filters are available with vertical/horizontal and soft/hard designations
- Vertical means the graduation line runs across the short dimension of the filter; Horizontal means the graduation line runs across the long dimension.
- Soft/hard indicates the degree of transition
Neutral Density factors
- ND.3 (exposure adjustment = 1 stop, reduces ISO 1/2)
- ND.6 (exposure adjustment = 2 stops, reduces ISO 1/4)
- ND.9 (exposure adjustment = 3 stops, reduces ISO 1/8)
- ND1.2 (exposure adjustment = 4 stops, reduces ISO 1/16)
