Thanks, Chadwell ji ---------- Forwarded message ---------- From: "C CHADWELL" <[email protected]> Date: 23 Feb 2017 8:48 p.m. Subject: An explanation for the difficulties Photographing 'Buttercups' (Ranunculus spp.) + the challenge of identifiaction of species in India To: "J.M. Garg" <[email protected]> Cc:
Attempting to get the exposure right for white and yellow-flowered plants (especially those with shiny petals) on sunny days is a challenge as they 'reflect' the light. It can be impossible with most cameras to expose correctly for both the flowers and darker green foliage. Most buttercups are yellow-flowered and thus fall into this category. The images posted on efI of Ranunculus spp. bear testament to this! However, they present additional difficulties, even in shady spots. The best I usually manage is a 'fair' exposure. Seldom am I comfortable with my photos of Ranunculus spp. I spotted a small piece in 'The Times' (of London) 22nd February 2017 entitled 'Secret of petal power' which appears to provide an explanation for our 'trials and tribulations' trying, often with little success, to photograph buttercups satisfactorily. Casper van der Kool of Laussane University has discovered the 'secret' behind the buttercup's shiny petals: an outer layer only one cell thick that hides an air chamber beneath. This "...acts as an optical film similar to oil on water of a soap bubble". It seems that butterflies use similar structures to produce colour. His findings are published in the Journal of the Royal Society Interface. See: http://rsif.royalsocietypublishing.org/content/14/127?current-issue=y Scroll down to LIFE SCIENCES-PHYSICS INTERFACE Functional optics of glossy buttercup flowers <http://rsif.royalsocietypublishing.org/content/14/127/20160933> Casper J. van der Kooi, J. Theo M. Elzenga, Jan Dijksterhuis, Doekele G. Stavenga J. R. Soc. Interface 2017 14 20160933; DOI: 10.1098/rsif.2016.0933. Published 22 February 2017 Having read the abstract (though not the full article), I find the brief summary of this within 'The Times' is incomplete. I recommend anyone interested, at the very least reads through the abstract, if not accesses the full article. I shall quote the first sentence of this Abstract, "Buttercup (Ranunculus spp.) flowers are exceptional because they feature a distinct gloss (mirror-like reflection) in addition to their matte-yellow coloration. *NOT that this helps with photographing the buttercups themselves - especially a high elevations where u.v.* *light is an additional consideration.* *AND there is the 'small' matter of correct identification of this challenging genus. I must wait and STEEL myself for the task of scrutinising this genus in the Himalaya along with the entries for it in eFI. It will not be a quick & easy task! I have images of Ranunculus taken in the Himalaya decades ago that I cannot, at present, identify with confidence.* Best Wishes, Chris Chadwell 81 Parlaunt Road SLOUGH SL3 8BE UK www.shpa.org.uk -- You received this message because you are subscribed to the Google Groups "efloraofindia" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. Visit this group at https://groups.google.com/group/indiantreepix. For more options, visit https://groups.google.com/d/optout.
