For Heavy storm or heavily contrasted clouds, brings to the sky a nice Emerald-1 color, which must be in harmony with the dominant color of your subject. Used up-side down, it brings back to the grass its natural green. Their color gradually fades out so the boundary between the colored and transparent sections will not become apparent even with the lens aperture stopped down.
A130 Emerald E1 requires one stop of compensation.
A131 Emerald E2 is twice the color density of E1 and requires 2 stops.
The Cokin A System comprises a complete range of COKIN filters for lens adaptor rings diameters 36 to 62 mm and Hasselblad® B50 as well as numerous dedicated accessories. The ”A Series” is recommended for focal lengths 35mm & greater.
For more information about, Cokin Gradual Emerald E1 Filter A Series A130 .