There are several different designations for neutral density filters. Such radiation absorbing filter optics are also called ND-filters, grey filters, OD-filters, or optical density filters. Neutral density filters are absorbing filter optics. They have a nearly constant transmittance which is largely color neutral and almost independent from the wavelength of the incidence light over a wide wavelength range. A great advantage of absorptive density filter optics is that their transmittance does not strongly depend on the incidence angle unlike it is the case for most filters based on optical coatings. The attenuation of an absorbing ND-filter is depending on the filter's thickness. The suitable NG grey-filter material and the appropriate density is selected under consideration of the desired target light transmittance, which is defined for the wavelength of 546nm (see table). Hence, almost any required filter density and therefore its transmittance can be adjusted by defining the thickness of the chosen ND-filter material. In practice the transmission is determined by test measurements of a raw grey-filter material which is then ground and polished to a calculated target thickness and that is then measured again. This way the transmittance of the finalized ND-filter is adjusted.
Neutral density filters are often used in photography in front of a camera lens for exposure correction. The filters attenuate the incident light that enters the camera lens to an acceptable level so a correct exposure can be obtained even if a lot of light is entering. For the conversion from density to transmission and vice versa we provide our "Optical Density <-> Transmission" converter program on a separate website. Likewise you can use our newly developed online-calculator for the calculation of the transmittance spectrum of any SCHOTT color glass filter. Also the transmittance spectra of any NG-grey-filter material can be calculated with our easy-to-use online application.
For laboratory use or for reference measurement applications, we manufacture OD-filter sets according to your density specifications and requirements. Please send us your inquiry in case you want to order an ND-filter set.
To request a quotation for neutral density filters made of a SCHOTT NG-grey-filter material with individual dimensions and custom transmissivity requirements please click the button below:
*The production of NG10 and NG12 neutral density filter materials has been discontinued. We only have a small stocks of those materials left.
NG 1, NG 9 and NG 10 ND-filters
NG 3, NG 4, NG 5, NG 11 and NG 12 ND-filters
For individual filter transmittance calculations please use our online-calculator for all optical glass filters from SCHOTT.
Light Transmittance of NG-Filter types
Further detailed filter characteristics on request.
All given details and specifications are mean reference values and are not guaranteed. In addition please consider our "Notes on technical specifications"