For Digital Cameras, or Film camera with B&W films. With a Digital, it can be used either in color mode or B&W mode. For Black & White mode, set the menu on "B&W" position and use it like a Film Camera.
In landscape photography and B&W mode, the Yellow filter improves the contrasts between clouds and sky. For portrait, it lightens the faces and blonde hair at the same time it softens freckles.