Saturday, October 12, 2019

On Chinese ZWB1, ZWB2, ZWB3 filter problems for reflected UV photography

Today about Chinese UV (ZWB1, ZWB2, ZWB3) filters intended for reflected UV photography. Those seem to be attractive, since the offered prices for instance on the portals ebay or Alibaba are far below the prices of such filters made from original SCHOTT or HOYA filter glass, both world renowed glass makers. I bought several ZWB1, ZWB2, ZWB3 filters for testing and two of them showed some effects worth knowing of, which I have never seen with Schott or Hoya filter glass.

[click on image gets you a larger image]

Here some examples shot in reflected ultraviolet (UV) light. UV filter used on my multispectral camera for reflected UV photography was a stack of Schott UG11 + S8612 ionic glass filters. A 365nm UV LED light was the light source. Background was a white 100x100mm Spectralon (R) calibration target.

These both were ZWB2 filter glass which its equivalent is SCHOTT UG1.

82mm ZWB2 filter in reflected UV (365nm)
52mm ZWB2 filter in reflected UV (365nm)
It gets quite visible that some very prominent striae, as defined in the International ISO 10110 Part 4 standard are prominent in these two samples. This in my opinion based on lack of suitable or careful enough Quality Control (QC) of the Chinese glass manufacturer (this maker here unknown) and may possibly occur in all those black glass filters, as it needs special equipment to do QC-checking using transmitted and reflected UV light.

Let me be very clear: I'm not stating that these issues will always be there or how likely these issues will be, as I have no data on this. Just be careful and test out your filters! For my part I will stay with SCHOTT or HOYA filter glass, as I never had any issues like that...


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, September 24, 2019

Shooting different wavebands using the same taking lens simultaneously

Today about a special contraption I have made, which allows to take images in different wavelengths, using the same lens simultaneously, and which even allows to compensate for focus shift within these wavebands.

[click on image gets you a larger image]

Here examples in visual light and reflected ultraviolet (UV) light, shot through the same taking lens. UV filter used was a stack of Schott UG + BG ionic glass filters. Sunlight was the light source as well as some help from a 365nm UV LED light.



I'm quite happy how well both the VIS an UV images are fitting in size:



I plan on revealing more about that solution later 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

Wednesday, September 18, 2019

The Bausch & Lomb f4.5 / 9" (229mm) lens for reflected UV II

Quite a few years ago I got an older lens, which was made many years ago by famous lens maker Bausch & Lomb, Rochester NY. It is a golden color coated, heavy and well made f4.5 / 9" (229mm) lens which attracted me, since it was made to record images displayed by a P-16 phosphor screen. Nothing special actually, but since P-16 phosphor emits at about max. 380nm, that attracted me most for my UV work.

 

A while ago I tested it against the Coastal Optics Micro Apo 105mm and the Nikon UV Nikkor 105mm and it perfomed very well.

[click on image gets you a larger image]

The spectrometric results in comparison to the Kuribayashi 3.5/35mm lens, one of the best performing "normal" lenses for UV reveals that is very useful for reflected UV:



The B&L lens has a very high UV performance, at 365nm it transmits 74%, whereas the Kuribayashi has 80%, so very close to it. A very useful long focal length lens for reflected UV with quite high UV transmission and reaching rather deep into the UV range for a non quartz fluorite lens.

So and here a few shots I took the other day with it, first the roof of the neighbour house about 20 meters away:


Then a Rudbeckia hirta flower on my balcony from about 4 meters away:

It is indeed a rather sharp lens for reflected UV, which allows a nice working distance, if so needed. A good addition to the rare tools for reflected photography!

I have written HERE more about it.

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, September 11, 2019

Garden in reflected ultraviolet photography and simulated bee vision

One of the most famous gardens in our area here in Weinheim, Germany is Schau- und Sichtungsgarten Hermannshof . Today I took some multispectral shots there, in normal human vision VIS, in UV using the Baader-U filter, as well as in simulated bee vision using my XBV filters respectively.

[click on image to get a larger view]

Human vision (VIS):


Reflected ultraviolet (UV):


Simulated Bee vision (BV):


Diptych VIS-UV:


Diptych VIS-BV:


This multispectral look at it reaveals a lot of otherwise invisible details, like the UV nectar patterns the yellow Rudbeckia flowers have. It wasn't my first time there, but certainly not my last time...

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, September 6, 2019

Oncostele Wildcat 'Golden Red Star' in visible, reflected UV, simulated bee and butterfly vision - 3D Stereo

Today shots of an Orchid hybride, Oncostele Wildcat 'Golden Red Star' in reflected ultraviolet photography as well as simulated bee and butterfly vision  - but also in 3D stereo crosseye presentation. UV filter used was the Baader-U filter, my "work horse" filter for reflected UV as well as my proprietary XBV filters. All shots were done at f8 using an UV-Nikkor f4.5/105mm lens. Light source used was a modified for high UV output Xenon flash.

[click on image to see a larger one]

Human Vision (VIS):
 

Reflected UV (Baader-U):
 

Simulated Butterfly Vision:
 

Simulated Bee Vision:
 

Quadriptych of the above (non-stereo):
 

This orchid has a very specific UV pattern, its petals are very UV dark, but the lower petal lip has on its lower center a very UV bright spot, as well as on its center "nose" formation an UV reflecting spot and all this gets nicely visible, also in 3D stereo (UV reflection shows as light blue)

I have written more about this orchid HERE and about Differentials 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, September 1, 2019

Spider Web reflects UV to attract prey II

I was reading some time ago a paper that spider webs would actually reflect ultraviolet (UV) light, so as to attract prey (insects like bees etc) and I shot this quite a while ago. Now it just happened again that I found a web in one corner of my balcony, so why not take some reflected UV and visible light shots and test it out? Lens used was my UV-Nikkor 105mm, for reflected ultraviolet light I used my "work horse" UV filter, the Baader-U filter. Light source was available light and some 365nm UV LED light.

[click on image yields a larger one]

Spider web in visible light (hardly visible at all) with some prey:


and now the proof that the web actually reflects UV light strongly:


Here two diptychs showing this side-a-side (visible light is left, reflected UV on the right):



Detail of the above:



Quite an interesrting find and another proof, how useful reflected UV photography can be!

I have reviously written about that 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

Wednesday, August 28, 2019

Black-eyed Susan - Rudbeckia hirta in reflected ultraviolet photography and simulated bee and butterfly vision 3D stereo XVI

Today more crosseye 3D stereo shots of another such beautiful flower, originating from the USA Prairie, a Black-eyed Susan - Rudbeckia hirta 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 f16. Lens was a UV-Nikkor 105mm quartz fluorite lens. Light source was a modified Xenon flash.

[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):
 

Also this flower shows a very prominent UV bullseye pattern, as its petal tips are very UV bright (around 365nm) and its center is very UV dark, and all this gets nicely visible in 3D stereo, also in simulated bee and butterfly vision.

I have previously written about that flower 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