Neutral Density Filter ( ND ) Description

A neutral density filter (ND filter) is a light filter that decreases the intensity of light without altering the relative spectral distribution of the energy. An ND filter is used to filter the entire visible spectrum evenly, allowing light reduction, without influencing color or contrast. For this reason, a neutral density filter is often referred to as a gray filter, or ND filter. Attenuation is accomplished by using either a light-absorbing glass or a thin-film metal coating that combines absorption and reflection. Metallic type neutral density filters obtain their optical density by depositing a metal alloy coating onto a specific type of substrate, which is determined by the wavelength region of interest. They are slightly sensitive to angles but they are much more forgiving than interference filters. A Neutral density filter (ND Filter) will attenuate spectral regions selected from 250 to 2500 nm. The level of attenuation can be specified from optical density 0.04 to 4.0.

Neutral Density Filter ( ND ) Operation

An ND filter reduces transmission either by reflection or absorption. A Reflective ND filter uses partial reflection to reduce light transmission evenly, while absorptive ND filters do the something using partial absorption. A variable ND filter, which changes the transmission linearly over time, is also available.

Neutral Density Filter ( ND ) Applications

An ND filter can be used with all types of film, but is especially valuable when working with high-speed films or long-exposure motion applications. When there is too much light, or a wide aperture is required, an ND filter may be used. An ND filter will diminish distracting backgrounds in a scene by permitting the use of wider apertures to reduce depth of field as required to throw the background out of focus while maintaining focus on the subject This allows for the emphasis of the subject by controlling depth of field or creating motion effect with subject blur. An ND filter will come with different levels of tint for fine-tuning exposures. ND filters of higher values are required for observation of the sun or when photographing smelters, arc welding, electrical generators, and other intense light sources.

Nd Filters – Neutral Density Filter

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• Circular Variable ND Filters: BK7 (375nm to 2000nm)
• Circular Variable ND Filters: Fused Silica (200nm to 2500nm)
• Circular Variable ND Filters: ZnSe (600nm to 15.0 microns)
• Circular Variable Neutral Transmission Filters: BK-7
• Circular Variable Neutral Transmission Filters: Fused Silica
• Fixed ND Filter Sets: BK-7 & Fused Silica
• Fixed ND Filters: BK-7 (375nm to 2000nm)
• Fixed ND Filters: Fused Silica (200nm to 2500nm)
• Fixed ND Filters: Infrared (2.0 to 14 microns)
• Linear Variable ND Filters: BK-7 (375nm to 2000nm)
• Linear Variable ND Filters: Fused Silica (200nm to 2600nm)
• Linear Variable ND Filters: ZnSe (600nm to 15.0 microns)
• Linear Variable Neutral Transmission Filters: BK-7
• Linear Variable Neutral Transmission Filters: Fused Silica
• Linear Variable Neutral Transmission Filters: ZnSe



• Click here to configure Neutral Density Filter (ND Filter)