A photographic or optical filter that absorbs light of all wavelengths to the same extent, causing overall dimming but no change in color.
- ‘Simulations of senile miosis using a pupil-constricting drug and the age-related increase in lenticular light absorption using a neutral density filter in young observers could not account for the results.’
- ‘Another use for this filter on sunny days is that it can be used as a neutral density filter in order to give you longer shutter speed times.’
- ‘We have also qualitatively tested the effect of reducing the incident light intensity by use of neutral density filters.’
- ‘An action spectrum for light-induced death was carried out using excitation filters and neutral density filters to vary the excitation wavelength and keep peak illumination intensity constant.’
- ‘Illumination was provided by a 150 W quartz halogen slide projector lamp attenuated by neutral density filters.’
We take a look at several popular, though confusing, punctuation marks.