Neutral Density (ND) Filters reduce overall light transmission evenly throughout a range of wavelengths.
ND Filters are characterized by a measure of percent transmittance through the filter or it’s Optical Density (OD) which describes the amount of light blocked. A filter with a low OD has higher transmission (OD 0.3 = 50% transmission), and a filter with a high OD has lower transmission (OD 2.0 = 1% transmission).
ND filters are additive and can be stacked to further reduce transmission. For example:
OD 0.6 (25%T) + OD 1.2(12.5%T) = OD 1.8 (1.5%T)
ND filters are most commonly used to reduce light intensity. They are used to reduce shutter speed to create blur or motion, and allow for a decreased depth of field. HeliOS offers a complete range of ODs in various sizes and shapes. Custom OD, sizes and shapes available. Please enquire with us for more details.
