I measured the Spectral Photon Distribution of the three CFA filters of a Nikon D610 in ‘Daylight’ conditions with a cheap spectrometer.  Taking a cue from this post I pointed it at light from the sun reflected off a gray card  and took a raw capture of the spectrum it produced.

An ImageJ plot did the rest.  I took a dozen captures at slightly different angles to catch the picture of the clearest spectrum.  Shown are the three spectral curves averaged over the two best opposing captures, each proportional to the number of photons let through by the respective Color Filter.   The units on the vertical axis are raw black-subtracted values from the raw file (DN), therefore the units on the vertical axis are proportional to the number of incident photons in each case.   The Photopic Eye Luminous Efficiency Function (2 degree, Sharpe et al 2005) is also shown for reference, scaled to the same maximum as the green curve (although in energy units, my bad). Continue reading Nikon CFA Spectral Power Distribution →