Our entire line of filters designed for the Nikon 14-24 2.8
A perfectly flat light transmission curve would yield a perfectly color neutral result. While this is technically impossible, the X4 CPL has the flattest transmission curve of any polarizer on the market - guaranteed. This translates into a more color neutral performance without a color cast.
A spectrometer is an optical instrument used to measure the properties of light across a spectrum. They can create spectral lines and measure their wavelength and intensity to determine the percentage of light that a filter transmits or blocks. The data are displayed as line graphs with light transmission % values for each wavelength measured.
The average light transmission % across the visible light spectrum is also an important metric to evaluate filter performance. Higher light transmission allows more light to pass through to the sensor, which translates into faster shutter speeds, sharper images and the ability to use a lower ISO when shooting video. The X4 CPL features the highest average light transmission - 47.18% - of any available CPL without sacrificing polarization efficiency.
Another benefit of high light transmission combined with a flat spectral curve is maintaining a consistent optical density or f-stop reduction throughout the visible range and well into infrared. The fractional transmittance of the the X4 CPL nearly matches an ideal 1-Stop (0.3) neutral density filter, giving the photographer or filmmaker a more dependable baseline to set up shots.
Spectrometer curves can be used to determine how much light a neutral density filter transmits across the spectrum. The flatter the curve, the more color neutral the filter.
Most of the neutral density filters on the market exhibit a strong blue cast which can be seen on a graph as an increase in % transmission in the shorter wavelengths (400 - 500nm). The X4 ND has the flattest transmission curve which translates into a more color neutral performance throughout the visible range and well into infrared.
Neutral density filters are designed to reduce light transmission to specific amounts depending on the optical density. Thanks to years of research and development, the X4 ND is incredibly precise to the ideal value.
An optimal 10-Stop (3.0) ND filter has a light transmission of 0.1% and with an average light transmission of 0.108% across the visible spectrum, the X4 ND hits the mark with great accuracy.