Tuesday, April 7, 2020

Reflected UV photography in polarized light IV - Saxifraga

Today more about UV polarizer experiments, using a special UV capable circular polarizer in front of my multispectral camera and UV-Nikkor 105mm lens, for recording polarized reflected UV images. Flower here was white Saxifraga - Rockfoil. UV filter used was my classic Baader-U filter; sun was used as light source.

[click on image gets you a larger image]

Here photographic results I got (took multiple images while rotating the filter), presented as animated gifs....

Saxifraga flowers through a rotating circular polarizer in A-mode i.e. exposure compensated...

Visible Light - Sunlight:



Reflected UV light - Sunlight:


Reflected UV light with 365nm UV LED:


Simulated bee vision - Sunlight:



This flower shows some interesting changes in polarization angle on the bottom of its flowers.  Bees have sensors on the outer ring of their compound eyes which are able to detect polarized light, so that might give this flower an advantage.

Reflected UV photography in polarized light shows quite some usefulness, especially if there are (glossy) surfaces which change the polarization angle of light and which the polarizer filter makes visible. Downside is that one needs about 2 stops more exposure, due to the low approx. 25% transmission.

Some insects are able to see the polarization angle (and btw. we humans can also, but needs some traing: Haidinger's Brush) especially honeybees which navigate using the polarization angle of ultraviolet (UV) light.

I have written more about using UV polarizers HERE

More about Saxifraga in multispectral photography is HERE

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, April 5, 2020

Reflected UV photography in polarized light III - Phlox

Today even more about UV polarizer experiments, using a special UV capable circular polarizer in front of my multispectral camera and UV-Nikkor 105mm lens, for recording polarized reflected UV images. Flower here was Phlox - Rockfoil. UV filter used was my classic Baader-U filter; sun was used as light source.

[click on image gets you a larger image]

Here photographic results I got (took multiple images while rotating the filter), presented as animated gifs....


Phlox flower in M-mode i.e. non exposure compensated:


Phlox flower in A-mode i.e. exposure compensated:



Reflected UV photography in polarized light shows quite some usefulness, especially if there are (glossy) surfaces which change the polarization angle of light and which the polarizer filter makes visible. Downside is that one needs about 2 stops more exposure, due to the low approx. 25% transmission.

Some insects are able to see the polarization angle (and btw. we humans can also, but needs some traing: Haidinger's Brush) especially honeybees which navigate using the polarization angle of ultraviolet (UV) light.

I have written more about using UV polarizers HERE

More about Phlox in multispectral photography is HERE

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

Phlox in reflected ultraviolet photography and simulated bee and butterfly vision

Today shots of some beautiful little hot pink flowers Phlox in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter, as well as in simulated bee and butterfly vision using my XBV filters. All shots were done at f11. Lens was a UV-Nikkor 105mm quartz fluorite lens. Light source was sunlight.

[click on image to see a larger one]

Human vision:
 

Reflected ultraviolet (UV):
 

Simulated butterfly vision:
 

Simulated bee vision:
 

Quadriptych of human vision, ultraviolet, simulated butterfly and bee vision (left to right, top to bottom):
 

This flower shows an interesting dark central ring UV pattern, its petals shine in UV (around 380nm), and all this gets nicely visible, also in simulated bee and butterfly vision.
 
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

Rockfoil - Saxifraga in reflected ultraviolet photography and simulated bee and butterfly vision II

Today shots of some beautiful little red flowers Saxifraga - Rockfoil in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter, as well as in simulated bee and butterfly vision using my XBV filters. All shots were done at f11. Lens was a UV-Nikkor 105mm quartz fluorite lens. Light source was sunlight.

[click on image to see a larger one]

Human vision:
 

Reflected ultraviolet (UV):
 

Simulated butterfly vision:
 

Simulated bee vision:
 

Quadriptych of human vision, ultraviolet, simulated bee and butterfly vision (left to right, top to bottom):
 

This flower shows no very prominent UV pattern, its petals transparently shine somewhat in UV (around 385nm), and all this gets nicely visible, also in simulated bee and butterfly vision.

I have previously written about Saxifraga HERE
 
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

Rockfoil - Saxifraga in reflected ultraviolet photography and simulated bee and butterfly vision I

Today shots of some beautiful little whitish flowers Saxifraga - Rockfoil in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter, as well as in simulated bee and butterfly vision using my XBV filters. All shots were done at f11. Lens was a UV-Nikkor 105mm quartz fluorite lens. Light source was sunlight.

[click on image to see a larger one]

Human vision:
 

Reflected ultraviolet (UV):
 

Simulated butterfly vision:
 

Simulated bee vision:
 

Quadriptych of human vision, ultraviolet, simulated butterfly and bee vision (left to right, top to bottom):
 

This flower shows no very prominent UV pattern, its petals somewhat transparently shine in UV (around 385nm), and all this gets nicely visible, also in simulated bee and butterfly vision.
 
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, March 29, 2020

Reflected UV photography in polarized light II

Today more about those UV polarizers experiments I have done, using special UV polarizers in front of my multispectral camera and UV-Nikkor 105mm lens, for recording reflected UV images. This now uses a UV transmitting filter for circular polarized light. UV filter used was my classic Baader-U filter; sun was used as light source.

[click on image gets you a larger image]

Here now more photographic results I got (took multiple images while rotating the filter), presented as animated gifs....

Roofs of some neighbouring houses showing strong polarizing effect of glass windows and metal:



Butterfly orchid - Phalaenopsis showing only mild polarizing effects:



Succulent plant - Lewisia showing strong polarizing effects:



Reflected UV photography in polarized light shows quite some usefulness, especially if there are (glossy) surfaces which change the polarization angle of light and which the polarizer filter makes visible. Downside is that one needs about 2 stops more exposure, due to the low approx. 25% transmission.

I have now solved the change of focus issue which I previously had.

Some insects are able to see the polarization angle (and btw. we humans can also, but needs some traing: Haidinger's Brush) especially honeybees which navigate using the polarization angle of ultraviolet (UV) light.

I will continue to make more tests later using the other polarizers and also the special waveplates, which allow for circular polarized light.


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

Wednesday, March 18, 2020

Reflected UV photography in polarized light I

Today about an experiment I have done, using a special UV polarizer made by Zeiss in front of my multispectral camera and UV-Nikkor 105mm lens for recording reflected UV images. This UV-Polarizer was especially made to work down to 300nm with some rather flat transmission and a 99-100% polarizing effectiveness in the 300-700nm range. It was part of a laboratory set of several UV-VIS-IR polarizers and wave plates I luckily acquired recently from a retired head of development. UV filter used was my classic Baader-U filter; sun was used as light source.

[click on image gets you a larger image]

Here the  transmission (linear scale) and absorbance (log scale) spectra of these polarizers:





Here now some of the photographic results I got (took multiple images while rotating the filter), presented as animated gifs....

Roofs of some neighbouring houses:




Flowering succulent plant (Cliff maids - Lewisia cotyledon):




Butterfly orchid - Phalaenopsis:



Reflected UV photography in polarized light shows quite some usefulness, especially if there are (glossy) surfaces which change the polarization angle of light and which the polarizer filter makes visible. Downside is that one needs about 2 stops more exposure, due to the low approx. 25% transmission.

Some may have noticed the change of focus, which might be caused by some unevenness of that special polarizing filter foil; it will be investigated later.

Some insects are able to see the polarization angle (and btw. we humans can also, but needs some traing: Haidinger's Brush) especially honeybees which navigate using the polarization angle of ultraviolet (UV) light.

I will make further tests later using the other polarizers and also the special waveplates, which allow for circular polarized light.


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