Spring Flowers 2014: Crocus flower dead vs alive - 80mm Quartz Fluorite lens for reflected ultraviolet photography

Today about something that caught my attention when I was out in the park shooting in reflected ultraviolet (UV) light, here a Crocus. It is the fact that a dead crocus flower dos not show the same colors in UV as one alive, which usually reflects around 385nm. This is not visible in normal light. Shots were done aside from visible photography in reflected ultraviolet light using my standard Baader-U filter. Lens used was my X80QF f3.2 / 80mm Quartz Fluorite lens. Light source was sun. All shots were done at approx. f8.

[click on image to see a larger one]

Visible light image:  

UV image using Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):  

Diptych of the above:  


This early spring flower shows its very specific UV pattern. Crocus usually is reflecting only in long wave UV around 385nm, visible as a bluish violet and its center (anthers, stamen) is UV dark. Its petals inside the flower are UV reflective, maybe caused by the shiny petal surface. But the dead one appears just grey as the stones around, wheras in visible light it looks like the one alive. Pure coincidence? I don't think so. Why should nature wate energy and attract a bee when there is nothing to gain for both sides? This older quartz fluorite lens is reproducing this quite well and all that gets nicely visible.

P.S.: a very alive spring Crocus (C. longiflorus) may be seen HERE

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

Spring Flowers 2014: Competing for bee attention - 80mm Quartz Fluorite lens for reflected ultraviolet photography

Well, spring finally seem to have arrived in Weinheim where I live, so here a few shots of some first spring flowers, Crocus and Winter Aconite, obviously competing for bee's attention. Shots were done aside from visible photography in reflected ultraviolet using Baader-U filter and in simulated bee vision using my XBV6 filter. Lens used was an older f3.2 / 80mm Quartz Fluorite lens. Light source was sun. All shots were done at approx. f8.

[click on image to see a larger one]

Visible light image:  

UV image using Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):  

Simulated bee vision image using experimental XBV filter:  


It is quite interesting to notice that Winter Aconite with UV reflection around 365nm and Crocus reflecting UV around 380nm are competing for bee's attention. I wonder which one wins, there haven't been many bees aroudn, mainly bumble bees, but I guess the Crosus does. This older quartz fluorite lens is reproducing this quite well and all that gets nicely visible.


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

Spring Crocus - Cerco 94mm Quartz Fluorite lens for reflected ultraviolet photography

Today about some early spring flowers, here Crocus (Crocus sp.) in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter. Lens was a CERCO 94mm quartz fluorite lens. Light source was sunlight. All shots were done at about f5.6. So, on to the results now...

[click on image to see a larger one]

Visible light image:
 

UV image using Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):
 

Simulated butterfly vision (UV - VIS) using XBV3 filter:
 

Simulated bee vision (UV - VIS) using XBV6 filter:
 

Quadtryptich of the above:
 


Crocus usually is reflecting only in long wave UV around 380nm, visible as a bluish violet and its center (anthers, stamen) is UV dark, which gets nicely visible 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

Spring Flowers 2013 - Cerco 94mm Quartz Fluorite lens for reflected ultraviolet photography

Today about some early spring flowers, Winter Aconite and Bellis perennis in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter, plus a new filter, consisting of a Schott UG1 + S8612 stack. Lens was a CERCO 94mm quartz fluorite lens. Light source was the last sunrays of that wonderful spring Sunday. All shots were done at about f5.6. So, on to the results now...

[click on image to see a larger one]

*** Bellis perennis ***

Visible light image:
 

UV image using Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):
 

UV image using Schott filter stack (approx. 320-400nm, effective peak approx. 375nm) but showing some bluish leak which the Baader filter does not have :
 

VIS-IR image using no filter:
 

*** Winter Aconite ***

Visible light image:
 

UV image using Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):
 

UV image using Schott filter stack (approx. 320-400nm, effective peak approx. 375nm) but showing some bluish leak which the Baader filter does not have:
 

VIS-IR image using no filter:
 

So, I hope you enjoy seeing some early spring flowers!


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

Filter leakage in reflected UV ultraviolet photography - unsuitable UV vs Baader-U filter III

Today again about IR leakage in reflected UV photography and how to deal with it. I have posted about that before here.

So what I wanted to show to today is, how different reflected UV images look like with and without IR leakage, so to enable a potential UV shooter to detect that. Images are presented in a side-a-side waqy, to make comparisons easier.

[click on image to see a larger one]

Here now the comparison with a commercially available UV filter, that not only leaks IR but also some blue vs the Baader-U 2" filter, Winter Aconite as target:

So here another example for very strong IR leakage (left), vs correct UV recording using a Baader-U 2" filter (right) using a strongly IR reflecting spring crocus as a target:


Same situation, but different angle and different crocus:

here in bw version, that shows that exposure was identical, but the pattern and structure is completely washed away by that IR leakage::

This following last example now shows the results of two different UV transmitting astro filters, left one with just a little IR leakage, but still enough to render the result useless, right the currently best filter for reflected UV in my opinion, the Baader-U 2", again using Winter Aconite as target:


Well, it was my goal to bring the attention to an often overlooked, but very important fact: IR leakage in reflected UV photography. Often beginners try to experiment with cheap UV transmitting filters, hoping to get some useful results. Unfortunately due to the very high IR sensitivity of modern sensors, just the tiny fraction of 0.1% leakage leads to useless results. So there is no way other than using highest quality UV transmission filters to secure useful results. Demand at least a IR suppression of OD3 from any UV transmitting filter, better even OD4!

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