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Anemone nemorosa [Wood Anemone] and Ranunculus ficaria [Lesser Celandine]: Comparison


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Rørslett, B. 2013. Comparing two common spring flowers, Anemone nemorosa L. (Wood Anemone) and Ranunculus ficaria L. (Lesser Celandine). (Ranunculaceae). Flowers photographed in visible and ultraviolet light, with multispectral composite. http://www.ultraviol...sser-celandine/

 

These are two spring flowers one frequently finds growing together on floors of rich deciduous forests. Both are native to Europe.

 

It may be interesting to compare these two with regard to their appearance in UV. Both species are frequently visited by smaller pollinators and the question is whether these receive visual clues of the respective targets.

 

Plants photographed in situ at Lindesnes, southern Norway 9 May 2007. I availed myself of a perfect calm weather to make long exposures without the need for using a flash source.

 

ANEM_NEM_RANU_FIC_I0705094619_VIS.jpg

Image reference: ANEM_NEM_RANU_FIC_I0705094619_VIS.jpg

Visible light: Nikon D200, UV-Nikkor 105 mm f/4.5 lens, Baader UV(IR Cut filter, daylight.

 

ANEM_NEM_RANU_FIC_I0705094616_UV.jpg

Image reference: ANEM_NEM_RANU_FIC_I0705094616_UV.jpg

Ultraviolet light: Nikon D200, UV-Nikkor 105 mm f/4.5 lens, Baader U 2" (Venus) filter, 5 sec. daylight exposure.

 

From the two images above, a multispectral composite is made by combining a monochrome version of the UV capture into the blue channel (B ), with the blue channel from the visible image into green (G), and green channel (G) of the same into red (R ). In principle this is a "bee-colour" composite for a hypothetical pollinator able to perceive UV, blue, and green colours.

 

ANEM_NEM_RANU_FIC_A07050946199_MS.jpg

Image reference: ANEM_NEM_RANU_FIC_A07050946199_MS.jpg

 

[Published 1 May 2013]

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Hi,

It seems that you like the idea of multispectral compositions. :D

That's exactly the way I combine them and the type of colours that I get.

I'm just wondering why the colours in your UV-images are so bright.

It might be the different camera model, or maybe the dedicated UV-lens, or the WB setting or the flash ...?

I would really like to find out.

 

Best, Nico

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Nothing mysterious about this, Nicolas. We do run the image files through a profiled setup in PhotoNinja (version 1.05 at present) in which a "UV white" balance has been set against spectrally neutral targets. Read more about the procedure here. You can get more or less the same result from other RAW processing programs. There is no magic involved. The profiling ensures that the targets are rendered with the same response in R,G,B. Most programs cannot achieve the required interchannel balance just by standard "click-white" operations and you may have to resort to using curve tools or similar. Save the result as a preset and apply to your RAW files later. Alternatively, store the profile in camera using the Custom menus found with many Panasonic cameras.

 

The main point here is that a normal grey card is unlikely to yield a useful "UV-white" balance. This will result in an overall colour cast to the images. Just like you commented.

 

Since you use a Panasonic camera there is a good chance you can get near perfect "UV white" balance if a better target is employed. Look into acquiring a piece of white or grey PTFE material. This is a cheap alternative to professional spectral targets, but do note they are not true Lambertian (diffuse) targets so do the balancing under overcast conditions.

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Andrea B.

Yes, the PTFE is very prone to producing blowout - especially with a camera lacking wide dynamic range.

After using the PTFE for an in-camera white balance setting, be sure to also take a Raw photograph of it

for further white balance calibration in your chosen converter/editor. This is important!

It may be that your in-camera white balance is excellent,

but sometimes you see a little variance depending on your ambient light or other factors.

 

It is useful to underexpose just a bit when shooting the Raw photo of the PTFE.

If the resultant PTFE photo is blownout, then the conversion can produce an awful, unwanted cyan

and further white balance calibration cannot be performed.

 

*****

 

Have we talked about colour space anywhere?

All our photos are converted to sRGB colour space for posting on the web.

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