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UV reflectance images

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#1 JMC

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Posted 21 March 2020 - 14:29

As some of you may know I suffer a lot with stress and anxiety, especially around large groups of people, so I tend to spend a lot of time at home when at all possible. UV imaging has meant that I can spend more time in the garden, especially in summer, and enjoy the wild flowers that grow there in different ways.

This is still one of my favourite images. It was taken with a Canon Eos 7D that was modified for UV by ACS in the UK, using one of their own filters. The lens was a Zeiss UV Sonnar on about 80mm of extension tubes to allow me to get closer to it, and below is the full frame shot and a cropped version. I was laying on the ground for this, with the camera balanced on a plank of wood, as my tripod wouldn't go low enough. I was sliding the camera back and forth to try and hit focus.

Attached Image: IMG_8394 2768k 1pt767 tint a mflenses.jpg

Attached Image: IMG_8394 2768k 1pt767 tint a cropped small.jpg
Jonathan M. Crowther

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#2 Stefano

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Posted 21 March 2020 - 14:35

Nice colors! They are very strong, I tried to photograph the same flower and it came out more on the orange side. You also get more lavenders than me, I usually get blue instead.

BTW, I didn't know that you suffer from stress and anxiety.

#3 Cadmium

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Posted 21 March 2020 - 15:22

Jonathan, Very nice shot. :-)

#4 Andy Perrin

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Posted 21 March 2020 - 17:59

Lovely photo! That species is one of the best for UV.

#5 nfoto

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Posted 21 March 2020 - 21:53

Buttercups can be very difficult to render properly in UV because of the high oil content in the honey leaves ('petals') near the basal nectaria, which leads to all kinds of shiny reflections and specular highlights. This is a first-class example that this obstacle can be overcome

#6 UlfW

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Posted 22 March 2020 - 07:25

A beautiful image!
It is perfectly composed and with well chosen focus.

I especially like the cropped version where I gradually discover more and more interesting details when looking, like the hairy parts below, showing up as silhouettes.

Just as Birna points out this flower can be difficult to photograph due to the risk of shiny reflections.
That was my first thought when I saw the first image.
She got first commenting that. I could not phrase it, that way, with such a learned vocabulary. :smile:
It is educating to read.
Is 'petals' not the correct word to use here?

There are several other flowers with shiny surfaces, but the Buttercup is one of the more difficult in this aspect due to the curvature of the petals.

Edited by UlfW, 22 March 2020 - 11:24.

Ulf Wilhelmson
Curious and trying to see the invisible.

#7 nfoto

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Posted 22 March 2020 - 10:47

Botanists themselves use 'petals' when they technically should not .... In this case, it is understandable. However, in Ranunculus it is a special structure in which nectaria are fused into what might have originated as a classic petal. Thus, we use the designation "honey leaf".

Botany has a very rich vocabulary, almost a language onto itself. Not easy to learn and if there is any consolation, I often keep forgetting the terms myself.

#8 nfoto

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Posted 22 March 2020 - 17:37

Here is an overview that might be helpful. Do note this is not directly applicable to Asteraceae (Daisy Family), the members of which have composite flowers in flower heads.

(from Wikipedia: Perianth)

Attached Image: 1040px-Mature_flower_diagram.svg.png

Perianth is the non-reproductive parts of a flower. The corolla is the collective term for petals (fused or single or in between), calyx the corresponding term for the sepals. It petals and sepals are indistinguishable, they tend to be lumped together as tepals.

The more common name for the 'microsporangium' is pollen sac, and the individual "spores" are pollen grains that collectively are known as pollen.

I did say this wasn't easy ... Also we note from the figure why the Buttercups have honey leaves with nectaria, not petals: two different structures are fused into one.

#9 Bill De Jager

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Posted 23 March 2020 - 23:55

Nice diagram and explanation. I've also seen tepals called perianth segments, though this was some decades ago.

#10 nfoto

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Posted 24 March 2020 - 00:08

Botany has a convoluted vocabulary .... Some species, for example the yellow water lilies, have seemingly large petals, but these are sepals that have been enlarged. The true petals are hidden on the inside of the flower. Just to illustrate how careful one must step across this mine field.

#11 Andrea B.

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Posted 25 March 2020 - 21:21

Jonathan, I'm so happy to hear that photography gives you some peaceful times in the garden. :cool:
Andrea G. Blum
Often found hanging out with flowers & bees.