Ho w to Measuring how light affects you
From the makers of f.lux, f.luxometer is an app that works with a spectrometer to measure light output in terms including melanopic lux, reflecting the spectral response of our daytime– detecting eye cells. At fluxometer.com/rainbow you can compare results from different screens. Taking an iPad Pro, at full brightness (pic 1) you can see the spike in blue frequencies. With iOS’s Night Shift activated at its default setting (pic 2), melanopic lux is cut by half. You could do that simply by halving the brightness, but here it’s achieved almost entirely by cutting that blue band, leaving the screen looking yellower but still bright. The f.lux Bedtime 1900K setting (pic 3) has a much more dramatic effect (sadly, iPad users can’t try this themselves because the iOS app isn’t approved by Apple). To get the same reduction in melanopic impact, you’d need to dim the brightness to just 12 per cent. You can use Night Shift and lower brightness in conjunction.