Jump to content
UltravioletPhotography

Using UV for research


msubees

Recommended Posts

Let us discuss what type of scientific experiments we can do with our tools...

 

reading 2 papers.

1. Horth, L, Campbell L and Bray R. 2014. Wild bees preferrentially visit Rudbeckia flower heads with exaggerated ultraviolet absorbing floral guides. Biology Open 3: 221-230.

 

in one of their figures, I did not understand why the sunscreen painted ones are grey under UV, they should be totally black? at least the inner petal should be the same darkness as the water control.

 

post-41-0-95855900-1460990471.jpg

 

In another paper (2).

Brock et al. 2016 Genetic architecture, biochemical underpinnings and ecological impact of floral UV patterning, Molecular Ecology 25: 1122-1140.

 

they did the same thing but at least the painted one looked very dark under UV.

 

post-41-0-49849700-1460990721.jpg

 

I suppose that in paper 1 they did not adjust the exposure to be the same for the 3 different treatments?

Link to comment
I think what we see is the classic error of using inadequate IR-blocking filters. Thus the "UV" image is really UV + IR.
Link to comment

I think what we see is the classic error of using inadequate IR-blocking filters. Thus the "UV" image is really UV + IR.

 

however their "air" and "water" images looked ok. so I thought it must be exposure adjustment?

Link to comment

No idea. Doesn't look right for sure.

 

Paper #2 commits the all too common error of designating a flower as "UV patternless", which we should know by now doesn't exist.

Link to comment

Horth, Campbell and Bray's 2014 paper states in their Materials and Methods that:

 

"UV photography was conducted using a Baader U-filter. This filter transmits UV wavelengths from 325 to 369 nm, with maximal penetrance in the UV-A range at 360 nm (Savazzi, 2011). The filter was used with an AF Micro Nikkor 60 mm lens, several mounts, and a Nikon D70 DSLR digital camera. UV photographs were downloaded to Nikon Capture NX2 software and then transferred to Image J 1.46 for quantitative analyses."

 

No mention is made about the camera being modified but it is listed in the Sticky as being one of the older CCD based Nikons rated as "Good unmodified" along with the D70S and D40.

 

The lens is not listed in the UVP lens Sticky.

Link to comment

I have the 60/2.8 Micro-Nikkor AF here, so I'll give it a try for UV. This is a truly terrible lens for IR, so I hope the same hotspotting does not show up in UV. Apparently not or we would have seen it in the above fotos.

 

I agree with Zach that the right-most Rudbeckia which is reportedly sun-screened does not all look as though it really is.

 

The 2nd paper is quite interesting to me because of their Brassica rapa examples which differ in UV pattern. We have seen a couple of examples like this. (If only I could remember which ones!!)

 

LATER: Found an example in Potentilla norvegica.

 

I found a flower which I was so sure was P. norvegica but it had no UV-dark proximal petal blotch so Bjørn questioned the ID. Now I am open to the possibility that it was indeed a P. norvegica with a variant UV-signature.

http://www.ultravioletphotography.com/content/index.php/topic/61-potentilla-norvegica-norwegian-cinquefoil/

Link to comment
The Brassica taxa are subject to heavy interbreeding as the wild races cross with their cultivated counterparts. Thus no problem understand why these might show variable UV signatures. However, for the mentioned Potentilla, no such explanation is likely.
Link to comment

Somewhere I speculated that it was really a P. rivalis. Except they do not grow where this one was found.

The guys in the paper could run actual genetic tests. That would be so cool if we could do that!

Link to comment

Somewhere I speculated that it was really a P. rivalis. Except they do not grow where this one was found.

The guys in the paper could run actual genetic tests. That would be so cool if we could do that!

 

I can run PCR tests to verify species, if there is a good scientific question and can result in a paper :P

Link to comment

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
×
×
  • Create New...