Hoya Fog filters come in two grades: A and B, and can be bought either separately or as a set.
- The "B" filter has a stronger effect than the "A" filter
- Both produce an "early morning fog-like" image the effect of which can be varied by stopping down the aperture on the lens
- These filters can also be used together to create an effect similar to dense fog.
- Stopping down too far will reduce the effect