B+W gray filters are available in a number of values (1, 2, 3, 6 and 10 f-stops) and permit wide aperture even when it is very bright for low depth of field and an interplay of sharpness and blur and/or long exposure times for motion blur or wiping effects (speed emphasis or flow of water). They also permit 'normal' time values and f-stop values when the film sensitivity is too high for the prevailing light. Gray filters with higher density (3 to 0 f-stops) are also used for technical photography, e.g. shots of lit lamp filaments, of combustion processes and procedures in melting ovens as well as for astrophotography.

CAUTION: These filters must not be used for the direct visual observation of the sun (they can cause severe burn to the retina up to total blindness!) since they transmit too much infrared for this purpose; special dielectric solar filters and AstroSolar Film are available for this.