The Cokin 121 series of filters comes in five variations of graduation
Cokin 121 - 2 stop Graduated Neutral Density
Cokin 121S - 3 stop Graduated Neutral Density (Soft)
Cokin 121F - 3 stop Graduated Neutral Density (Full)
Cokin 121L - 1.75 stop Graduated Neutral Density (Light)
Cokin 121M - 1.75 stop Graduated Neutral Density (Medium)
Cokin graduated gray ND filters are part clear, part neutral density
They allow the transition to be blended into the scene, often imperceptibly
A ND.6-to-clear, with a two stop differential, will generally compensate the average bright sky-to-foreground situation and is also the most popular density of the series
Type
Graduated Soft Gray Resin Filter
Size
4x6" (100 x 150mm)
Grade
G2
Filter Factor
3 stops ((exposure adjustment = reduces ISO 1/8)
Multi-Coated
No
Rotating
No
Effect
Balanced light intensity from one part of a scene to another
Application
Nature, Travel, Outdoor photography; To maintain light control, as in bright contrasty landscapes; i.e. bright sky, dark foreground