Tuesday, December 11, 2018

Baader-U Venus filter versus OPTOLONG Venus-U filter

Today about a new (to me) UV transmitting filter for reflected ultraviolet (UV) photography: the 2" OPTOLONG VENUS-U filter. This filter I have compared here with my work-horse UV filter, the 2" Baader-U Venus filter.

First it is about the resulting images and of course if there might be any IR leakage. The latter is quite important, as in early morning or late evening sunlight, where IR is predominant or when shooting against the sun or when reflective elements are present in an image,  IR leakage may lead to loss of contrast, or even obscuring the wanted UV details.

Now on to my tests which have been done using as a target an Oncostele orchid which has quite some prominent UV marks. Lens used was an UV-Nikkor 105mm, camera a modified Panasonic GH4, light a modified for high UV output Xenon studio flash. All shots were one at f8.

[click on image to see a larger one]

Baader-U filter (left) vs Optolong Venus filter (right:

Baader-U filter (left) vs Optolong Venus filter (right) - whitebalanced against gray BG:


It gets quite obvious that there is something going on here in terms of leakage, as the image shot with the Optolong Venus filter shows some blueish hint visible all over the orchid and also there is some central flare visible, wheras the Baader-U Venusfilter delivers a tack sharp and high contrast image. After whitebalacing against the gray background, which obviously was not possible with the Optolong filter, the result gets even worse, a rather muddy looking image results from the Optolong filter. In terms of exposure, the Baader U filter also has a slight 0.3 stop advantage over the Optolong filter.

Once I will have done some spectrometric transmission measuerements, I will certainly post those here later.

So please draw your own conclusions from this, if you would consider this a valuable filter for reflected UV photography. I will certainly continue to use my "work-horse" UV filter, the Baader-U.

I have written about IR leakage in filters for reflected UV photography 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

University of Zurich Zoological Museum exhibit «Insects - essential to life!»

The Zoological Museum of the University of Zurich, Switzerland has just opened the doors of a new special exhibit "Insects - essential to life!". IT will be on display December 11, 2018 - June 30, 2019.

Included in this is a video with some of my best multispectral works, which my partner for this, animation artist Robin Noorda, has converted into a video presentation, named "Insecta Spectra".

Some insects (butterflies, Bees, ...) and also some animals (birds, fish, degus,..) are able to see ultraviolet (UV) light. Bees for instance can see Green and Blue and UV, but no RED, but butterflies and birds can see Red, Green and Blue and UV, so both can see what we humans cannot see - UV. To make that visible for us humans, I developed a special filtering and optical mapping method, which allows to simulate, how we would see the world, if we had such special UV receptive eyes.

Have a look at the preview video clip [click]:


Certainly and exhibit worth visiting with the whole family!

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, December 3, 2018

Oncostele Wildcat 'Golden Red Star' in visible and reflected ultraviolet (UV) light

Today shots of an Orchid hybride, Oncostele Wildcat 'Golden Red Star' in reflected ultraviolet photography with a UV-Nikkor f4.5/105mm lens. UV filter used was the Baader-U filter, my "work horse" filter for reflected UV. All shots were done at f8 for the UV-Nikkor. Light source used was a modified for high UV output Xenon flash.

[click on image to see a larger one]

Visual vs reflected UV (Baader-U):
 

This orchid has a very specific UV pattern, its petals are very UV dark, but its lower petal lip has on the 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.

I have written more about this orchid 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

Saturday, December 1, 2018

[UV, VIS, IR] Lyman Alpha deep UV lenses V - Oncostele orchid

Today shots of a Orchid hybride (Oncostele Wildcat 'Golden Red Star') in reflected ultraviolet photography with a NYE OPTICAL Lyman-Alpha I f2.8/100mm UV-VIS-NIR lens. UV filters used was the Baader-U filter for the Lyman Alpha 100mm, rear mounted. All shots were done at f2.8 as the Lyman Alpha lens has no iris. Light source used was two different Nichia 365nm UV-LEDs, one a cheap Convoy S2 UV mini torch.

[click on image to see a larger one]

For reference, visible light shot (UV-Nikkor 105mm):
 

Lyman Alpha I lens UV using Baader-U filter and Convoy S2 UV LED:
 

Lyman Alpha I lens UV using Baader-U filter and Convoy S2 UV LED:
 

Lyman Alpha I lens UV using Baader-U filter and strong Nichia UV LED:
 

This orchid has a very specific UV pattern, its petals are very UV dark, but its lower petal lip has on the 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 with this Lyman Alpha I f2.8/200mm mirror only lens.

I have written about the Nye Lyman-Alpha lenses previously HERE and about this Orchid 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, November 29, 2018

Common Sunflower - Helianthus annuus in reflected ultraviolet photography and simulated bee vision II

Today more shots of a flower everybody has already seen, a common Sunflower - Helianthus annuus in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter as well as in simulated bee vision using my XBV filter. Lens was my UV-Nikkor 105mm quartz flourite lens. Light source was sunlight. All shots were done at f8.

[click on image to see a larger one]

Human vision:
 

Reflected UV:
 

Simulated bee vision:
 

Triptych of human vision, UV, simulated bee vision (left to right):
 

This flower has a specific and unique UV pattern, its petal tops are brightly UV reflective around 365nm and the rest and its center is UV dark forming an UV bullseye pattern, and all this gets nicely visible, also in simulated bee vision.

I have written about sunflowers 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

Wednesday, November 28, 2018

[UV, VIS, IR] Lyman Alpha deep UV lenses IV - Oncostele orchid

Today tests shots of a Orchid hybride (Oncostele Wildcat 'Golden Red Star') in reflected ultraviolet photography with a NYE OPTICAL Lyman-Alpha II f1.1/90mm UV-VIS-NIR lens in comparisoon with my UV-Nikkor 105mm lens. UV filters used was the Baader-U and the IDAS 340nm filter for the UV-Nikkor and a UV transmitting stack of UG11+S8612 as well as a 340nm filter for the Lyman Alpha 90mm, both rear mounted. All shots were done at f4.5 for the UV-Nikkor resp. f1.1 as the Lyman Alpha lens has no iris. Light source used was Xenon flash.

[click on image to see a larger one]

UV-Nikkor 105mm Visible Light:
 

UV-Nikkor 105mm Baader-U filter:
 

UV-Nikkor 105mm Baader-U filter (whitebalanced):
 

UV-Nikkor 105mm 340nm IDAS filter:
 

Lyman Alpha II 90mm UG11+S8612 filter:
 

Lyman Alpha II 90mm UG11+S8612 filter (whitebalanced):
 

Lyman Alpha II 90mm 340nm filter:
 

UV-Nikkor vs Lyman Alpha II 90mm in UV:
 

UV-Nikkor vs Lyman Alpha II 90mm in UV (whitebalanced):
 

UV-Nikkor vs Lyman Alpha II 90mm in UV (340nm):
 
This orchid has a very specific UV pattern, its petals are very UV dark, but its lower petal lip has on the 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.

Both lenses are very different animals so to speak, that Lyman Alpha II f1.1/90mm has extremely shallow DOF as compared to the f4.5 / 105mm UV-Nikkor lens, as well as some bent field, but it shows a very useful UV transmission. That rear mounted 340nm seems not to be the clearest filter, as the resulting image was a bit cloudy, not the fault of the lens.

I have written about the Nye Lyman-Alpha lenses previously HERE and about this Orchid 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

Saturday, November 17, 2018

ZUFAR 4/350mm and its prototype quartz fluorite catadioptric lens III

Today again about that Quartz Fluorite catadioptric ZUFAR-2CA f4/350mm anastigmat lens which had been developed for the Soviet MARS 2 to 5 missions to planet Mars. I'm rather excited to report that I  found and bought the grandfather of this ZUFAR-2 space lens from planet Mars exploration, a prototype lens with a very different internal name Ob-512, but company data (LOMO) I was able to locate confirmed my suspicion, it is indeed one or even "the" factory prototype of it. 





Top Ob-512 prototype, Bottom: ZUFAR-2CAM lens

The prototype OB-512 also was made of synthetic Quartz and Calcium Fluorite (CaF2) crystals to be able to work in UV and also visible light, designed for 200-700nm without focus shift, so actually is an apochromatic (APO) f4.7/350mm catadioptric lens as per its lens passport. Lens transmission is >57%. Viewing angle is approx. 3 degrees (later 4 degrees). Image diameter 24.6mm. 51mm back focal length. Its weight is 2.2 kilograms, which was later changed in the final ZUFAR-2 CA lens to 1.8 kg using special alloys, as every gram counted then for space missions.

Those ZUFAR lenses have been designed in the 70s under the lead of Institute head and chief designer Prof. Volosov together with N. Khmelnikova, I. Driatskaya, K. Mikhailova at GOI, the russian state lens design institute in St. Petersburg / Leningrad. Details were published by Prof Volosov in 1974.

(Made for my use by my dear friend Marco Cavina)


Optical data of the Ob-512 prototxpe as per Volossov et al.

This lens was made to be used on a very elaborate camera system which could take multispectral images on film, develop that and scan it and send the scanned data back to Earth in selectable resolutions (up to 2000x2000 pix, which took over one hour to transmit).


NASA also wrote about this lens (quote):

Zufar objectives were used on the television cameras carried by the Mars-2, 3, 4, and 5 spacecraft. The compact catadioptric quartz-fluorite anastigmat was developed as a result of research on the possible optical arrangements of lens and mirror-lens systems meeting the rigid criteria for spaceborne operation. The system is characterized by precise correction of all aberrations over a broad spectral range, about 300-700 nm. The spectral transmission is about 60% over this range. The Zufar-2CA version of the objective has a geometric aperture ratio of 1:4 and a focal length of 350 mm. The image format is 24 x 24 mm. The housing is 164 mm long and 130 mm in diameter, and the mass of the objective is 1500 g.

Here one of the published images from Mars taken on Mars-5 mission:



The lens will be given a suitable adaption to fit my digital multispectral cameras and I will certainly take multispectral photos with it as soon as possible and report about here later on.

Data of this lens, as well as its normal (= non catadioptric) quartz fluorite sister lenses with shorter focal length may be found on my macrolenses database site HERE

There is more about this lens HERE.


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