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ND Filter

ND Filter

Neutral density filter (ND filter) can reduce or modify the intensity of all wavelengths or the color of light equally, having no impact in hue of color condition. It can be a colorless (clear) or grey filter. The purpose of a standard photographic neutral density filter is to reduce the amount of light entering the lens. By doing so, the photographer can select combinations of aperture, exposure time and sensor sensitivity which would otherwise produce the overexposed pictures. This is done to achieve effects su shallower ch as a shallower depth of field and/or motion blur of a subject in a wider range of situations and atmospheric conditions.

The performance of a neutral density filter is defined as its Optical Density (O.D)

Neuteal density filtery or ND filters are "grey" filters. They are used to reduce transmission and increase contrast. Kupo neutral density filter is ideal vecause it reduces light of all wavelengths or colors equally.

NDF-001 Reference color #LEE209
400~700nm Tavg = 40% ± 3%
NDF-002 Reference color #LEE210
400~700nm Tavg = 20% ± 3%
NDF-003 Reference color #LEE211
400~700nm Tavg = 6.5% ± 1.5%
NDF-004 Reference color #LEE299
400~700nm Tavg = 2.5% ± 1%
  • O.D = Log10 ( Io/ IT )
  • Where Io = Incident Energy
  • IT = Transmitted Energy


  • Optical glass (Range : 400mm to 200nm)
  • Fused Silica (Range : 250mm to 1200nm)
  • Surface/Coating Quality : F/F per MIL-F-48616


  • Optical Instruments
  • Lighting
  • Measuring Instrument