Jim Lloyd Posted May 4, 2018 Share Posted May 4, 2018 Ha - Just bought a flower identification app - and so far its auto identification has worked (n=2!) This plant grows like a weed literally right outside our door (and at times even attempts to encroach inside!) [Hexham, North East England, May]- I have been know to rip it up like a weed - maybe I will start to think differently now ? Images similar to those on this site already (here, here and here ) but I was taken particularly in my examples by the gold and silver appearance of the leaves in UV D3200 full spectrum conversionUG1 2 mm + BG40 2 mm for UVBG40 only for visiblePhotax 35mm f/3.5 old preset version with extension tubef/16. Full Sunlight outside early afternoonWB and processing in LightroomASA 400 4seconds for UV / ASA 100 1/50 s for visible Link to comment
Jim Lloyd Posted May 4, 2018 Author Share Posted May 4, 2018 Sorry - posted in the wrong forum section (should have been UV experiences ?) - Not sure how to move. Link to comment
Andrea B. Posted May 4, 2018 Share Posted May 4, 2018 I moved it to the Ultraviolet Photographs section. Yes, some foliage can have a metallic look in UV due to a strong iridescence. That can happen for various reasons - cellular surface characteristics or leaf coatings like a waxy cuticle or other reasons. I love seeing this little flower growing on brick walls or on garden stones. I saw C. muralis growing on some old bridges in Venice where it was very charming in that rustic setting. It seems to be very hardy stuff. Link to comment
Andy Perrin Posted May 5, 2018 Share Posted May 5, 2018 Yes, some foliage can have a metallic look in UV due to a strong iridescence. That can happen for various reasons - cellular surface characteristics or leaf coatings like a waxy cuticle or other reasons. The reason UV is particularly prone to it is that refractive indexes of most things are much higher in UV than in visible. The percent of light reflected (at normal incidence, for a given wavelength) is R = ((n-1)/(n+1))^2, where n is refractive index at that wavelength, so a bigger n means a bigger percentage of the light is reflected. Link to comment
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