Tiffen 77mm Neutral density Filter is a solid neutral density filter providing 2 stop exposure

Tipo Solid neutral density 0.6
Dimension 77 mdiameter 5mm thick
Grade 0.6 (2 stops)
Filter factor Reduce ISO 1/4
Multilayer NO
Rotating NO
Effect Lowers the brightness uniformly throughout the scene.
Application When the ratio of brightness exceed the the latitude of the film or you need longer exposure time or a greater iris aperture obtaining a shorter field depht.
Colour Temp. No changes
Material Glass
Front Filter Thread Size 77 mm

Short guide ND filters:
ND.3 (adjust exposure = 1 stop, reduce ISO 1/2)
ND.6 (adjust exposure = 2 stop, reduce ISO 1/4)
ND.9 (adjust exposure = 3 stop, reduce ISO 1/8)