Neutral density filters: theory vs. reality

Keywords: Neutral density filter, Optical filters, Transmittance, Grey filter


Neutral density filters in theory do not affect the shape of the spectrum of radiation that traverses through them. In practice, real neutral density filters are far from being truly neutral and do alter the spectrum of radiation. Not all neutral density filters alter the spectrum to the same extent or in the same way. We here compare the spectral transmittance of six readily available neutral density filters and consider how their effect on the light spectrum can have implications for their use in light sources used in scientific research and on camera lenses used for imaging.

Author Biography

Pedro J. Aphalo, University of Helsinki

University Lecturer, Principal Investigator

How to Cite
Aphalo, P. J. (2020) “Neutral density filters: theory vs. reality”, UV4Plants Bulletin. Helsinki, Finland, 2019(1), pp. 51-60. doi: 10.19232/uv4pb.2019.1.15.