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UltravioletPhotography

Rosa sp. [Striped Rose]


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Blum, A.G. (2013) Rosa sp. L. (Rosaceae) Striped Rose. Flowers photographed in ultraviolet and visible light. http://www.ultraviol...p-striped-rose/

 

Middletown, New Jersey, USA

14 February 2014

Purchased at Grocery Store

 

Comment:

Striping in roses may be either a genetic trait or one cause by certain kinds of viruses which break the uniformity of rose petal pigments(1). I was curious whether these Valentine's Day red striped roses would show their stiping in UV. The answer is interesting.

In the UV false colour photos made with the Baader-U UV-Pass filter, some blue UV false colour appears to generally indicate the lighter Visible red striping, but there is no obvious UV-light/dark striped patterning. When these Baader-U UV images are subsequently desaturated to remove all false colour, then the rose appears to have no striping whatsoever in UV. So we must be careful how we interpret false colours in UV fotos.

In UV false colour photos made with the Precision-U filter, which has slightly different transmission than the Baader-U, there less obvious false colour differences in the area where the Visible stripes would be.

 

Reference:

1. American Rose Society (2014) Striped Roses by Dr. Lakshmi Sridharan. http://www.ars.org/striped-roses/

 

Equipment [Nikon D600-broadband + Nikon 105mm f/4.5 UV-Nikkor]

 

All fotos below may be clicked, then clicked again for the largest view of 1200 pixels in a fully expanded browser.

 

Visible Light [f/11 for 1/8" @ ISO 100 with onboard Flash and Baader UVIR-Block Filter]

rosaRedStripedVisFlash021414wf_16632pnRes.jpg

 

Visible Light [Desaturation of previous photo]

Obvious striping remains when the Visible photo is desaturated.

rosaRedStripedVisFlash021414wf_16632pnResDesat.jpg

 

Ultraviolet Light [f/11 for 15" @ ISO 400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

A long exposure was used in order to fire the flash 3 times for even lighting.

The dark blue UV false colour areas do match the larger Visible stiping patterns to some extent.

rosaRedStripedUVBaadUSB14021414wf_16641pnRes.jpg

 

Ultraviolet Light [Desaturation of previous photo]

There is no evident striping in the desaturated version of the UV photo.

Question: Can we conclude that the false colour in the preceding UV foto is meaningless?

rosaRedStripedUVBaadUSB14021414wf_16641pnResDesat.jpg

 

Visible Light [f/11 for 1/20" @ ISO 100 with onboard Flash and Baader UVIR-Block Filter]

rosaRedStripedVisFlash021414wf_16593pnRes.jpg

 

Ultraviolet Light [f/8 for 15" @ ISO 400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

A long exposure was made so that I could fire the UV flash 3 times for more even lighting.

The reflected UV light reveals the intricate, delicate texture of the rose petals.

rosaRedStripedUVBaadUSB14021414wf_16612pnRes.jpg

 

Ultraviolet Light [f/8 for 15" @ ISO 400 with SB-14 UV-modified Flash and Precision-U UV-Pass Filter]

There is a slightly different, more monotone false colour rendition when using the Precision-U.

However, further editing could perhaps bring out another colour.

Please see additional comment below.

rosaRedStripedUVPrecUSB14021414wf_16611pnRes.jpg

 

Visible Light [f/16 for 1.6" @ ISO 400 with onboard Flash and Baader UVIR-Block Filter]

A longer than usual flash exposure was made with a very low flash output to give a gentle fill.

rosaRedStripedVisFlash021414wf_16644pnRes.jpg

 

Ultraviolet Light [f/16 for 10" @ ISO 400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

rosaRedStripedUVBaadUSB14021414wf_16656pnRes.jpg

 

Ultraviolet Light [f/16 for 15" @ ISO 400 with SB-14 UV-modified Flash and Precision-U UV-Pass Filter]

The Precision-U UV-pass filter has a slightly different transmission peak than the Baader-U and so, under this particular edit, provides a more delicate false colouration which does not as obviously track the Visible striping on the petals - although it is there.

rosaRedStripedUVPrecUSB14021414wf_16648pnRes.jpg

 

Visible Light [f/16 for 1/10" @ ISO 400 with onboard Flash and Baader UVIR-Block Filter]

rosaRedStripedVisFlash021414wf_16687pnRes.jpg

 

Ultraviolet Light [f/16 for 15" @ ISO 400 with SB-14 UV-modified Flash and Baader UV-Pass Filter]

Again, the reflected UV with its shorter wavelengths puts the texture and veining of the petals' surfaces into stronger relief as compared to the Visible surfaces.

rosaRedStripedUVBaadUSB14021414wf_16697pnRes.jpg

 

Ultraviolet Light [A crop from the full-sized version of the preceding foto.]

Conical cells are evident in the textured surface of the rose petals.

Lean back a bit from your monitor to view this crop properly.

It will look a tad fuzzy if you are too close.

rosaRedStripedUVBaadUSB14021414wf_16697pn100Crop.jpg

 

Visible Light [f/8 for 1/40" @ ISO 400 with onboard Flash and Baader UVIR-Block Filter]

These petals were beginning to curl at the edges as the rose aged.

I pulled them down a bit to show the striping.

rosaRedStripedVisFlash021414wf_16620pnRes.jpg

 

Ultraviolet Light [f/xx for xxx" @ ISO XXX with SB-14 UV-modified Flash and Baader UV-Pass Filter]

The false UV dark blue colour mostly matches the larger paler-red areas in the Visible photo.

rosaRedStripedUVBaadUSB14021414wf_16624pnRes.jpg

Link to comment

Thank you, Col.

Roses are quite lovely in UV for their texture and 'glow'. Do try some shots yourself.

 

In a reversal of the norm, I did buy 8 striped red roses to give to my honey on Valentine's Day !!

He bought me a delicious heart-shaped strawberry-topped cake, so it was a fair trade. ;)

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As long as there are a large number of conical cells, incidence angle of light is very important in shaping the final photographic outcome. I would never issue a statement of something natural is 'meaningless'.
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Oh la !! ;)

The strawberry cake lasted about 5 minutes !!

 

*********

 

Bjørn wrote: I would never issue a statement of something natural is 'meaningless'.

 

Bjørn, assuredly I am not "issuing a statement" about false colour being meaningless !!! :rolleyes:

Please read carefully: that was a question designed to get some input from people.

I have added two more question marks (in my typically overwrought style) to make it clear that this is a question.

REPEAT: Can we conclude that the false colour in the preceding UV foto is meaningless ???

 

But to be clearer, I have edited the first comment in the post:

OLD: So we must be careful not to attribute too much meaning to false colours in UV fotos.

NEW: So we must be careful how we interpret false colours in UV fotos.

 

I was hoping for some discussion about what false colour means in UV fotos when it is not associated with an underlying UV-light/dark patterning - as seen in this striped rose.

 

I note for the record (if nothing else) that false colours are not "natural". :P They are partly an artifact of the Bayer filter. And it is pretty easy to get the false colours in UV fotos to change by a little tweak of the colour wheel or the white dropper. How stable are false colours, especially if not associated with a typical UV signature??? I have often thought we should also provide a desaturated version of our UV shots. Indeed, I may try to do that as it could be interesting.

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