Heliopan Grau 4x ND 0.6 Filter (2 stop) - Baj.II/3.5Heliopan Grau 4x ND 0. 6 Filter Baj. II 3. 5 Made in: Germany Diameter: Baj. III 3. 5 Ambitious or professional photographers will at some stage reach the point where both the setting options of the camera and the spectrum of the film is exhausted. Sometimes the photographer simply wants a longer exposure time than the camera can offer, to achieve a properly exposed image. For example this can be the case if the sensitivity is already set to the