Warren told me it would be interesting for some of you to know what happens when we try to avoid over-exposure. Well, here are my first results.
Direct sunlight is too strong. One way to reduce intensity is to use only a reflected part of it. I used plain white paper for the next two spectra. In the first I aimed at a shadowed part of the paper:
Reds and greens are low (so that yellow and turquois are missing). No second (middle) red peak anymore. Almost no light at 600 nm.
Now I show you a spectrum of sunlightthat was reflected off the brighter part of the paper (without shadow).
Some more light at 600 nm but still no yellows at all, no turquois. Some flickering in the "waterfall" picture and some darker small lines in the green and blue part. Have those lines any meaning? Between 420 and 480 nm the blue curve looks "too flat" somehow. I am not sure if that is just co-incidence.
Here you can see the combined (overlayed) intensity curves:
Blue part of the spectrums is almost the same, red is only a bit reduced. The main difference is in the green range between 480 and 590 nm. Again, blue seems to be the colour of the shadows.
The worst over-exposure happens in the green range. It seems that using light reflected off white paper helps against over-exposure but it affects the whole spectrum by swallowing parts more or less completely (and more than other parts! The whole curve changes.). Perhaps there are other ways to reduce light intensity without changing the spectrum too much. Perhaps we should try polarisation filters???