Precision Molded Aspheres - SUMITA OPTICAL GLASS Inc. - aspheres
Bestsewing light magnifier
Neutral density filters are essentially gray filters designed to equally reduce the amount of light hitting the camera’s sensor, thereby increasing exposure times. Neutral density (ND) filters are most useful when a long exposure time is desired but not attainable given the available lighting.
Neutral density filters have gradings associated with the amount of light they reduce. The higher the grading, the more light is reduced, and the wider the aperture or slower the shutter speed can be set. ND filters are commonly rated by the density of the filter. For each filter density of 0.3, the camera’s f-stop is reduced by 1, and the darker the filter will appear. The below chart explains a wide array of ND filters, the associated density, and the amount of f-stop reduction.