Wednesday, July 30, 2008

X-lenses help to discover the Secret of Bats with UV vision



Recently researchers have found out (Nature, 9. October 2003 p. 612-614) that many bat species seem to have a sensitivity to ultraviolet (UV) light, which is more abundant at dawn and dusk. The colour-blind Long-tongued Nectar bat (Glossophaga soricina) for instance is sensitive to UV down to a wavelength of 310 nm. Experiments at Universities in Guatemela and Erlangen, Germany revealed a sensitivity in the green (max. 510 nm) and UV (>365 nm) spectra. The same very same photoreceptor was responsible for both peaks in the green and the UV. Quite interesting to note since in all rodents and marsupials with colour vision, there is a separate receptor which handles UV light.

Link to the original publication of the Max Planck Institute, Germany

The University of Ulm, Biology Dept., Germany has decided to equip their two year long lasting Panama expedition, starting spring 2008, together with the US Smithsonian Institute with two calibrated for UV lenses, my X135 and X35, to help to discover the secret of bats with UV sight there. These bats live from fig fruits which are supposed to carry marks only visible in UV. 

First interim results now show, that indeed there seems to be UV marks at these fruits which come from the wax coated surface. [click on image to see a larger version]



[top images curtesy and (C) Universtiy of Ulm; processing and UV remapping by me]

Top left shows a sample of that Panamanean fig fruit in visual light, top right in UV light shot using the calibrated for UV X-lenses. Bottom left and right shows UV remapped into the visual domain to enhance the UV pattern present.

["X-lenses" denotes a series of lenses which are calibrated for UV photography. Up to today there are the X28, X35, X50, X90, X135 and longer lenses available, the number after the "X" denoting the focal length. These allow for high quality reflected UV photography at a fraction of the cost of these specialized fluorite/quartz lenses]

So I hope you found that as interesting as I do....

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Tuesday, July 29, 2008

Dive into the Beauty of Rudbeckia fulgida flower

So, again, the same setup as before - how boring? I'm just excited (pun intended, since it is fluorescenece...) about that beauty of that Rudbeckia fulgida flower, so let's dive into that a bit more, using some old lens I always wanted to try out, and vo√≠la, that is one great little razor sharp gem (and no, it it not one of my loved Zeiss Luminars)!

What we see in the second picture is UV induced visible fluorescence, using my Nichia 365nm UV LED lamp as exciter. No filter was used in that case, so what we see here is a mix of visual and some reflected UV light.

The flower center, as may be seen in the second shot, has a very strong UV reflectance, even if it appears dark brown/black in the visible shot. One may assume that this is intended together with the highly reflective UV pattern at the end of the flower petals, to attract pollinators like a "helicopter landing port".

[As usual, a click on an image opens up a larger one.]

Visual shot:




UV induced fluorescence shot:




So I hope you like it as much as I do....

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Sunday, July 27, 2008

A comparative, subjective shootout of Lenses for UV Photography ... Fluorescence

So, same setup as before, but what we see here is UV induced visible fluorescence, using that Nichia 365nm UV LED lamp as exciter. No filter was used in that case, so what we see here is a mix of visual and UV light. Actually this creates quite a test case for UV lenses, since it clearly shows, how well both wavebands (UV + VIS) are corrected in terms of focus shift.

UV Rodagon 60mm:



EL Nikkor 3.5/63mm:



X50 calibrated lens for UV 50mm [looks differently since I had another light on...]:



X90 calibrated lens for UV 90mm:



X135 calibrated lens for UV 135mm:



And now, a few days later, that rare UV Rodagon 150mm.
UV Rodagon 150mm:



So I hope you also found these results useful....

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Saturday, July 26, 2008

A comparative, subjective shootout of lenses for reflected UV photography


Now this will be a rather lengthy entry I presume, so be forewarned! Why you might ask? Well today I got a request and di a comparative shootout of various lenses for UV, using that Rudbeckia fulgida flower as a target, ca. 80mm (3.1") in diameter. The Baader U-filter was used, as well as Xenon lighting and UV LED lighting (365nm).

The candidates were the classic UV Nikkor 105mm, the Coastal Optics Micro Apo 105mm, the UV Rodagon 60mm (making up the group of the most expensive ones), then the EL Nikkor 3.5/63mm enlarger lens and my calibrated lenses for UV in 50mm, 90mm and 135mm focal length (X50, X90, X135).

Here now the results, and as usual here, a click on a picture opens up a large version of it.

UV Nikkor 105mm:

Visual shot:



UV shot:



Coastal Optics Micro Apo 105mm:

Visual shot:



UV shot:



UV Rodagon 60mm:

Visual shot:



UV shot:



EL Nikkor 63mm:

Visual shot:



UV shot:



X50 calibrated lens for UV 50mm:

Visual shot:



UV shot:



X90 calibrated lens for UV 90mm:

Visual shot:



UV shot:



X135 calibrated lens for UV 135mm:

Visual shot:



UV shot:



And now here a few days later a rare find, the results using an UV Rodagon 150mm. The flower has aged of course...

UV Rodagon 150mm:

Visual shot:



UV shot:




But now you're up to you to interpret....

[Just some hints: be careful when comparing the images, since the working distance had to be very different due to the different focal lengths used to achieve about the same magnification. So you will notice, that although the same aperture f8 was used, the depth of focus is different. This is because of the changed angle of view, and has nothing to do with a lens being more or less sharp.]

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Thursday, July 24, 2008

Bumble Bees on Rudbeckia fulgida (B. xanthopus, B. canariensis)



Here now a shot showing two types of Bumle Bee on Rudbeckia fulgida, Bombus xanthopus (left) and Bumbus canarienses (right).

Visual shot:




UV shot:




UV remapped into the visible domain now yields:




So, I hope you like that, too.


Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Friday, July 18, 2008

Rudbeckia fulgida and X135 calibrated lens for macro


As shown before, Rudbeckia fulgida shows quite an impressive UV pattern, but there is more to discover. So using my famous calibrated X135 lens, a tilt/shift bellows, the great Baader U and UV/IR Cut Filter and my 365nm Nichia UV LED the following may be seen [click on image to see larger images]:

Visual shot:


UV shot:



UV induced visible flourescence shot (UV not suppressed):


UV induced visible flourescence shot (UV suppressed, using Baader UV/IR Cut filter):



So it may be seen that the pollen shows some impressive fluorescence, but also the other inner parts of the flower show different flourescence patterns!

Let's now have a look at how bees might see that now using my "bee vision algorithm" which remaps UV into our visual space as blue, so as if we had UV sight :




It is quite obvious, that the flower center has some strong UV reflectance which most likely help to attract pollinators such as bees and bumble bees. And the following picture now would be the bee's view (since bees don't see red):




The calibrated for UV X135 lens has again proven, how great it works for visual and UV shots, also for macro.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Thursday, July 17, 2008

UV pattern of a Bumble Bee on Rudbeckia fulgida


A Bumble Bee on a Rudbeckia fulgida shows it impressive UV pattern, as does the flower! Here the visual shot first [click on image to see much better and larger images]:




The outer petals reflect UV much stronger than the inside of the flower, as it the flower would create a "landing spot" for the Bumble bee. The following shot shows the UV reflection:





I find it quite fascinating that the abdomen of the Bumble Bee reflect UV so strong as if it would like to tell its colleagues "This one is taken for now...". I wanted to find out more about it and created a synthesized "bee vison" version of that one, a bit differently than usual by remapping the UV image into the visual space so that the UV reflecting abdomen gets clearly visible. Quite obviously that has the same UV reflection than the flower center.
Just pure coincidence? I guess not.....!





Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos