Sunday, September 1, 2013

Rudbeckia fulgida vs Helianthus spp in reflected ultraviolet photography and simulated bee vision

Today shots of two decorative flowers, made of Orange coneflower - Rudbeckia fulgida in comparison to small sunflower - Helianthus spp in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter as well as in simulated bee vision using my XBV6 filter. Lens was my CERCO 94mm quartz flourite lens. Light source was sunlight. All shots were done at about f5.6.

[click on image to see a larger one]

Visible light image  

UV image using Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):  

Simulated bee vision image using experimental XBV filter:  

Triptych of the above images:  

This comparison is intended to compare our human vison, where both flowers appear nearly identical to our eye, yet bees and other UV sensitive insects cleary see a big difference - a UV bullseye pattern! The Rudbeckia flower (on the left) shows a UV dark bullseye pattern on its petals, invisible to us humans, and the flower center is quite UV dark, whereas the Helianthus flower (on the right) shows no UV pattern at all, except its UV dark center and UV bright petals, and all this gets nicely visible in direct comparison. Actually I saw many more insects visiting Rudbeckias as they were visiting Helianthus, maybe just a coincidence, maybe based on that bright UV pattern Rudbeckias have. Would be interesting to find that out...

Stay tuned, more will follow on that fascinating subject...