Today a little different topic: I would like to show, how a flower (R. hirta) achives a competitive edge over other flowers (Monardia, Echinacea) by making use of a specific intense UV reflection around 365nm, matched to the insect eyes sensitivity. This will be shown using a flower originating from the USA Prairie, a Black-eyed Susan - Rudbeckia hirta and it will be done in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter aside from a visible light shot. Lens was my UV-Nikkor 105mm quartz flourite lens. Light source was sunlight. All shots were done at f8.
[click on image to see a larger one]
Visible light image (400-750nm):
Reflected UV image using Baader-U filter (320-395nm):
Diptych of visible image (left) and reflected UV image (right):
In visible light, all flowers are rather bright to our human eye. But this R. hirta flower in UV (only visible to bees and butterflies) shows a very prominent and bright bullseye pattern, as its petals are very UV bright (around 365nm) and its center is very UV dark, compared to the rather dull UV reflecting Monardia and Echinacea flowers (around 380nm only), hence creating an impressive competitive edge in terms of chances for getting pollinated - and all this gets nicely visible.
Stay tuned, more will follow on that fascinating subject...