Monday, June 12, 2017

White balancing options: SPECTRALON (R) versus sintered PTFE versus virgin white PTFE / Teflon (R)

Today a spectrometric test of materials used for white balancing of reflected UV photography: SPECTRALON (R) calibrated reflection standard made and sold by company LABSPHERE, sintered porous PTFE (porous filter discs, as used in filters for chemical processes and medicine) and virgin white PTFE (white extruded industrial material for various purposes sold as plates, cut discs etc.) to see which of these materials would be suitable for the UV-VIS range of 300 - 700nm. Many years ago I had proposed to use virgin white Teflon (R) / PTFE as a cheap and easy to get material.

[click on image to see a larger one]



The 100% (green, hard to see) line is the reflection of the SPECTRALON (R) reflection standart as sold by LABSPHERE and is used as a refence. The yellow line indicates the reflection of some seemingly sintered PTFE, now sold as white balance filter mounted into filters rings (52mm in this case), originally made and sold as 50mm porous filter material for chemical and medical purposes. This latter material reflects rather evenly between 80-83%. The virgin PTFE in comparision has a more uneven reflection of 72-75% (>320nm), down to 68% below 320nm. For amateur photographic purposes the two cheaper materials provide sufficient evenness, with an edge in favour of the sintered PTFE. For professional applications, both are however no alternative to the industry standard SPECTRALON (R) which shows outstanding evenness.

Remark: all such materials are extremely sensitive to dirt, fingerprints etc. which reduces the UV reflection massively, so have to be kept clean at all times and need to be cleaned asap if so contaminated. Best to clean is to brush with ethanol, then rinse with purified water, then let dry in a dust and lint free environment or dry with pressured clean air.

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

Monday, May 8, 2017

Petri Kuribayashi 35mm vs Kyoei Acall 80mm lens for reflected UV photography VI

Today a spectrometric test using that previously mentioned Petri Kuribayashi f3.5/35mm lens, compared to a Kyoei Acall f3.5/80mm lens in M44 thread mount, as a proof that both actually have a very useful lens transmission, especially in UV.

[click on image to see a larger one]



The Kuribayashi 35mm still reaches deeper into UV, even a bit below 320nm and shows a rather high UV at 365nm transmission of over 80%. However the Kyoei Acall f3.5/80mm short tele lens seems to be quite similar, reaches beyond 340nm and has a 70% UV transmission at 365nm, just 10% lower!

I have written about that lens before 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

Thursday, April 6, 2017

Petri Kuribayashi 35mm vs Kyoei Acall 180mm lens for reflected UV photography V

Today a spectrometric test using that previously mentioned Petri Kuribayashi f3.5/35mm lens, compared to a Kyoei Acall f3.5/180mm lens in M42 thread mount, as a proof that both actually have a very different lens transmission, especially in UV.

[click on image to see a larger one]



The Kuribayashi 35mm reaches much deeper into UV, even a bit below 320nm and shows a rather high UV at 365nm transmission of over 80%. However the Kyoei Acall f3.5/180mm tele lens seems to be a very different beast, as it has no useful at all UV transmission!

I have written about that lens before 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

Petri Kuribayashi 35mm vs Kyoei W. Acall 35mm lens for reflected UV photography IV

Today a spectrometric test using that previously mentioned Petri Kuribayashi f3.5/35mm lens, compared to the W. Acall f3.5/35mm lens in Leica Thread Mount (LTM), as a proof that both actually have a very different lens transmission, especially in UV.

[click on image to see a larger one]



The Kuribayashi 35mm reaches much deeper into UV, even a bit below 320nm and shows a rather high UV at 365nm transmission of over 80%. However the similar looking W. Acall 35mm seems to be a very different beast, as it has at 365nm only approx 5% UV transmission, so basically none useful at all!

I have written about that lens before 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

Tuesday, January 17, 2017

Gasometer Oberhausen Museum, Wonders of Nature Exhibit extended until end of 2017 IV

Gasometer Oberhausen Museum has reported a record breaking visitor count of 750.000 by end of 2016 for their "Wonders of Nature" exhibit  and has hence decided to extend until November 30, 2017. I have participated in that with some of my works in large prints and a video presentation. An impressive location it is, the highest Museum in Germany (116m high, 66m wide) showing some amazing exhibit areas inside:

(C) Gasometer Oberhausen

My contribution are some images of a Zinnia haageana flower in large prints, on display in their exhibition area below that 20 meter large earth globe, demonstrating the difference between our human vision, as well as a video presentation shown on LCD panel which originates from the BBC series "How to grow a planet - The hidden World of UV" which has several of my VIS and UV images of different flowers in it.


Gasometer Oberhausen, video presentation of my works: visible and ultraviolet images of the same flowers, showing nectar guides, invisible to us humans, but visible to bees!
Posted by Klaus Schmitt on Friday, March 11, 2016
Printed Zinnia (in UV light) in background, video display in foreground:


approx 3m / 9ft wide Zinnia image in ultraviolet light:


Zinnia haageana: Triptych of Human Vision, UV, Simulated Bee Vision (left to right):  

The exhibit shows in total some 150 large images and video presentations by the most famous nature photographers and is not only visually stunning, but also highly educative and suited for interested individuals as well as families and schools. Go have a look, it will be well worth it!

There is still a printed book available about it: Wunder der Natur, Die Intelligenz der Schöpfung ISBN/EAN: 9783837514629 (in German language)

I have written about that exhibit previously HERE

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

Monday, January 9, 2017

Moth orchid - Phalaenopsis in reflected ultraviolet photography and simulated butterfly and bee vision

Today studio shots of a decorative flower, Moth orchid - Phalaenopsis in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter, as well as in simulated butterfly and bee vision using my proprietary XBV filters. Lens was my UV-Nikkor 105mm quartz flourite lens. All shots were done at about f8. Light source was a modified Xenon flash, background was dark gray. [These shots were done with a new camera system and are available on request in very high resolution (40 and 60 Mp)]

[click on image to see a larger one]

Visible light image
 

UV image using Baader-U filter:
  

Simulated butterfly vision image:
  

Simulated bee vision image:
  

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

This attractive flower shows a not so prominent UV pattern around its labellum , and all this gets nicely visible also in simulated butterfly and bee vision.

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