Friday, December 14, 2007

A simple tutorial for UV photography

[Remark: this on is an older, outdated version. For the newer V2 of this go HERE. ]

I have been asked to write down a simple "cook book style" tutorial on UV photography, so here it comes:

1) get a suitable lens, uncoated or single coated, simple lens design like a triplet. You have to try things out, some work, some don't. EL Nikkor enlarger lenses are not bad, get a 75 or 80mm. Also the Wollensak Graphic Raptars seem to have a useful UV transmission, but quite some focus shift. The best you can get is the UV Nikkor 105mm, but that is quite some costly $$$$ investment.

2) get a suitable filter. The new 2" Baader U-filter is the best you can get, >80% within 310...390nm transmission, IR perfectly suppressed, which is important for most DSLRs due to their high IR and low UV sensitivity especially if your camera has the internal filter removed. Be prepared to expose 8 stops more than normal. My usual setting on an sunny to overcast day is 2..4" @ f11 ISO200 using a Nikon D70.

3) get a suitable UV enabled camera. My finding is that the Nikon D70(s) is the best value for money for UV as is the D40. D80 and D200 are said to work well either, but need the internal filter removed first. CANON shooters - sad day, it does NOT work with Canon DSLRs, their filters and CMOS chips do not allow to record UV in an acceptable manner (see the test I have published here; extremely long exposure, high ISO, noisy results).

4) Use a sturdy tripod to allow 2...4" exposure time, sometimes much longer though. UV is strongest 90 degrees to the sun, don't shoot in bright sun, due to high IR content (no longer a big problem with the new Baader 2" U-Filter!)

5) for comparison shots I shoot visual light first and then attach the filter and shoot UV with exactly the same framing. Be careful not to move the camera. If using an older lens, focus closer. This needs to be tested out, my finding is that the f8...f11 position on the DOF scale works best. Shot RAW files or high resolution JPEGs. Pro's do RAW, but for simple testing JPEG will do.

6) Upload pictures and process pictures. They will look very red, but what you see is UV, depending on camera mainly in the green and somewhat blue channel (D70). So either you process them to black/white or whitebalance them. Then adjust to taste. UV has no "color" by definition, so you may do what you like.

7) for an UV differential combine the visual and UV shot as you like and depending on software used. I use a special one and do the UV-VIS as a mathematical operation on pixel level.

8) enjoy the sometimes strange and exotic results!

This is in condensed form the result of some years of research and test. So if you need some advice or equipment, let me know, I have plenty of filters, lenses etc. available, since I tested so much for the last years.

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

More info on this very interesting field may be found on my site

Thursday, November 15, 2007

The strangest lens for UV I ever found...

Today it is about one of the strangest lenses for UV photography I ever found: a Wollensak 4" f4.5 UV Anastigmat and that is its fascinating story (which I have been told by the former owner and will now be put forward as it came...):

"Late in 1950 there was a number of large iron metorites that landed in the northeast of the United States. Upon examination a great many had a solid and perfect core of a crystalline substance that resembled the finest of optical glass. The owner of Wollensak being a man of quirk and varied interests decided to purchase a number of the meteorites and to saw them, grind and polish them to make a few lenses. The meteors were quite large but the glass was quite brittle so in the end only a few lenses were made...this being THE one, the finest, the 'sample' of the series.

The lens seemed to have a fire within itself, no doubt due to the experiences and conditions that the crystal was made..flying at untold speeds for untold millenia over millions of miles. The sky is a big place, the galaxy is even greater. This lens...oh this lens, is something very special. It seems though to have been at the center of a number of accidents at the factory.

While the cutting took place, a shard flew from the block and pierced both eyes of machinist, later during the polishing process a young apprentice caught his sleeve in the polisher which broke his wrist then as he struggled with his other arm in a vain attempt to free himself he managed to catch that one too. It snapped like a twig, he fainted and fell forward at which point the collar of his shirt was caught in the polisher and it snapped his neck.

Truly a sad tale of woe which cannot be entirely brushed away with coincidence. While the lens was being coated it was noted through the window that the magnesium fluoride wasn't melting so the technician entered the oven to adjust the thermostat only find that the oven was on, in seconds his clothing was on fire and he was completely disfigured. While all this commotion was going on small chirps were heard to come from the lenses, some say it was the glass contorting in the mounts while others was the lenses laughing."

Here now the results of using this lens, first the visible shot:

And this is the UV shot using the 2" Baader U-Filter (310..390nm); that lens is not corrected for UV focus, so finding a sharp image is somewhat tricky:

So what have we here now? This is a differential between the two shots above, showing in one picture compressed the visible light and the UV shot. It clearly reveals how metal strongly reflects UV, and so does the sky:

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

More info on this very interesting field may be found on my site

Thursday, November 1, 2007

Simulated Bee Vison III

It is again about Bee Vision. Here now something I am currently making up my mind about:

These first two images are the visual and the ultraviolet shot:

and now different UV remapping algorithms would be possible, to simulate how bees would see, taking into consideration that they only see UV, B, G and we see B G R channels.

1) This one now transposes or maps the "Bee Image" linearly down into our color space:

The linear color mapping results into quite some red in the resulting image.

2) This one maps the "Bee Image" non-linearly and compresses the UV a bee can see into our short wave spectrum (which I have to admit won't work well with blue or violet flowers):

This non-linear mapping now maps into our complete human visible spectrum.

3) This one is like the one above, but takes into consideration that bees can't see red, so the red channel is suppressed.

Since all these three mappings have a "scientific base" I am still making up my mind which one I like best, but I personally tend towards #2...

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

More info on this very interesting field may be found on my site

Friday, October 19, 2007

Simulated Bee Vision II

Today it is about simulated Bee Vision which I find quite fascinating. Bees and some other insects do see ultraviolet (UV) light, what we humans cannot (with the exception of some people, but that is another story...). So I wondered how that would look like if I could see with bee eyes.

I tried to simulate that by adding an ultraviolet and visual picture together after some tricky aligning plus I suppressed the red channel which bees don't have. Here now the results, UV is mapped into the resulting picture as blue.

The leftmost shot is the visible one, the center is the UV shot and the one on the right the simulated Bee Vision. Some other examples:

So what would we humans see, had we UV receptors? That I guess...

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

More info on this very interesting field may be found on my site

Friday, October 12, 2007

Nichia 365nm UV LED based UV lamp ... first results

[update: there is a much more powerful system available now based on the new Nichia 4 dice chips NC4U133 (365nm) and NC4U134 (385nm), which has about 3.5x the power]

I just got an UV lamp/flash based on the powerful 250mW Nichia NCSU033A 365nm UV LED which was specifically made for my photographic goals.

Here now the first pre-production sample and some results. It is made to operate from mains but also from battery (8..16Volts) so would also allow portable operation for many hours. The LED is built into a cooling cylindrical housing and will also be equipped with an adaptor for an UV light guide (quartz or liquid). Power is adjustable from 0...100% and I have also foreseen a 10% and 100% switch. To trigger that via the camera is the next thing to work on.

This is how the first sample looks like, nice I would say:
[click on image yields a larger version].

The emitted wavelength depends a bit on the power the LED operates at, but the shift is small (367 @10% vs. 369nm @ 100%), see attached spectras. The output of visual light is indeed very small, but of course visible esp. at full power.

@100% Power [normalized Intensity, not absolute output]:

@10% Power [normalized Intensity, not absolute output]:

The UV LED showed only minimal long term drift due to thermal effects of ca 0.7nm 
(from 370.0 to 370.7nm after 20mins @100%); start temp: 20 degrees, end temp ca. 42 degrees Celsius. The green line was the center wavelength at start, the blue line  shows the minimal shift of that wavelength over time thanks to the excellent control 

Now on to the photographic results using that UV LED. Target here was a Rudbeckia flower, since it sports a nice UV pattern.

VISUAL shot:

UV induced visual FLUORESCENCE (using Baader UV/IR Cut filter):

UV (using Baader 2" U-filter):

UV + UV induced visual FLUORESCENCE (no filter, shot in darkness):

Unaltered shots directly from the camera, just sized down.

And here some test using synthesized DOF for the UV shot:

and some shot from the side in much higher magnification using UV Rodagon 60mm + Baader UV/IR Cut filter to show the fluorescent pollen:

100% crop:

So in total I would find that litte gem quite useful...

Even more so since now it has been enhanced, so a camera is able to trigger the unit as long as the shutter is open to full power and then falls back to a preadjusted value. Quite nice, so one is not exposed to full power all the time and handling is much easier.

A further enhancement is an adjustable f1 quartz condensor lens which allows to focus/defocus the UV beam depending on the lighting situation needed. Plus there is also now an adaptor to a quartz or liquid light guide to direct UV light as needed.

P.S.: There are now also different LED heads available, such as a 385nm head, white light with different color temperatures (3500 - 8000 K) plus for IR (850nm and longer)

P.P.S.: there is now also a holder for a camera hotshoe which makes operation very easy.

A laser pointer also fits in to make it easy to target:

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

More info on this very interesting field may be found on my site

Wednesday, September 26, 2007

Dive into the wonders of the Mexican Zinnia

Today I would like to invite you to a journey into the wonders of the Mexican Zinnia, which is one of my favorites for UV shooting, since it has so much to offer.

Equipment used was two Macro Nikkors 35+19mm, a modified Olympus variable extention tube and a 375nm UV LED light. All shots were done at ISO400 to capture the faint fluorescence, thus the higher amount of visible noise.

So this was the one from a previous session...[click on image yields a larger version].

Now let's dive in...

and deeper...

Now let's switch modes from "visible and fluorescence" to "UV and UV induced visible fluorescence":

and deeper...

and deeper...

and deeper....reaching about 14x magnification on CCD, on screen ca 160x...

So this wonderful little flower has it all, a nice visible appearance, a sharp UV pattern, fluorescent petals, pollen and stems (even in different color!)...

Lenses used were Macro Nikkor 35mm+19mm on a modified Olympus variable extention tube + RMS mount adaptor. UV LED 375nm. Camera used was the Olympus E-510.

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

More info on this very interesting field may be found on my site

Tuesday, September 18, 2007

UV and the Quantum Computer Research

UV seems to be important to researchers, too.

I have been asked for advice by the University of Ulm/Germany which is part of the European Quantum Computer Project. Single Calcium ions are catched and isolated into a special fabricated deep temperature trap and targeted by laser radiation which brings them to emit UV light at about 397nm. To record this very faint radiation, a special lens is needed which has enough working distance, highest resolution and UV transmission. After some tests in my lab my advice was to use a Carl Zeiss Luminar 63mm for that purpose, which still has some 70% transmission at this wavelength.

Regarding resolution, the 63mm Luminar has a resolution of about 330lpm using white light and about 600lpm at ultraviolet /UV) light.

So enjoy some pictures from the forefront of research with me here; courtesy and (c) Institute for Quantum Information Processing, University of Ulm, Germany.

Experimental Setup showing a deep temperature dewar and laser injection:

Deep temperature Ion Trap:

Carl Zeiss Luminar 63mm as recording lens for 397nm Ca+ emissions (rear):

Recorded UV Ca ion emissions @397nm:

[All images in this thread (c) Institute for Quantum Information Processing, University of Ulm, Germany, used with permission]

More on the (various) series of Zeiss Luminar macro lenses, pictures, data etc. may be found on my site together with some 300 other special macro lenses.

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

More info on this very interesting field may be found on my site

Monday, September 17, 2007

Canon DSLRs for UV?

I was a Canon shooter, always, for many years. Then something happened, I got infected by that "UV Photography Virus" and I switched to Nikon. Why? Easy answer, some Nikon DSLRs are pretty sensitive to UV, but Canons are not. Are they really?

So I did a test after some years of having neglected my Canon gear and shot using the Canon 20D and the Nikon D70 under otherwise identical conditions.

And the winner is...??

Here's the Canon 20D result:

And here is the Nikon D70 result:

Not much visible difference, right? But the real difference gets visible when we have a look at the exposure data:

- Canon:  EOS 20D, ISO3200 (!!!), 30sec, f5.6, UV Rodagon 60mm, Baader 2" U-filter, UV LED

- Nikon: Nikon D70, ISO200, 2sec, f5.6, UV Rodagon 60mm, Baader 2" U-filter, UV LED

which is about 8EV (!!!) in favour of the Nikon D70 - a clear winner for UV shooting.

That now does not mean you can't use a Canon DSLR at all, it is just that ISO3200 and 30sec exposure are not really that convenient if you shoot somewhat ambitiously UV, irrespectively of the much higher noise which occurs at that high ISO level.

(Remark as of 2017: Canon cameras also use SONY sensors now, no own developemnts, so also Canon cameras have useful UV sensitivity from what I have read and seen)

Ultra Achromatic Takumar 300mm for UV

So I also have this ultra rare Pentax Ultra Achromatic Takumar f5.6 300mm sitting in my cupboard and I wondered how that would perform in UV.

Just opposite my house is that little mountain about 2 kilometers away and just ideal to take some shots from the upper window of the Windeck castle. It turned out that this lens is razor sharp and produces nice differentials (difference between the visible and the UV shot).

It was slightly sunny, around noon (not ideal for shooting UV actually).

The second shot is the differential and shows how the UV shot differs from teh visual obe. Colors were somewhat adjusted to taste.

The detail resolution is quite astonishing for that lens, which may be seen here on the explainatory plate which is about legible from 2ooo meters!

So I guess I like that lens!

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

More info on this very interesting field may be found on my site

Saturday, September 15, 2007

Carl Zeiss Jena 60mm UV-Objektiv and Rudbeckia

So today I dug out my old Carl Zeiss Jena f4 60mm UV-Objektiv (a simple triplet actually, made of UV transmitting glass) mounted it with a suitable helicoid to an Olympus E-510 DSLR, and repeated the reflected UV and fluorescence shots as yesterday.

As light source a 365nm UV LED was used here and no other modifications were done. Here the UV shot using the Baader 2" U-filter (320-390nm), just color balanced to taste, no other modifications done. Interesting to note that since this lens is a simple, yet sharp triplet design, quite some massive focus difference between visible focus and UV shows, nearly 50mm in this case (closer for UV). [actually also the reason why the UV image is somewhat larger]

The second shot I used the same UV LED, but the filter used was the Baader UV/IR Cut filter, to suppress UV and to allow for fluorescence.

Oh, and if someone wondered how that flower looks like in normal white light, there you go...

Did you notice these aphids wondering around...? It seems to grin right into the lens on that last shot!

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

More info on this very interesting field may be found on my site

Friday, September 14, 2007

Steinheil Quarz f1.8 50mm and UV LEDs

So since the UV-LEDs for UV photography seem to work quite nicely, here now some results using very old (1933) and very recent (2007) technology hand-in-hand. It is (again) that Steinheil f1.8 50mm Quarz Objektiv (quartz lens) mounted with a suitable helicoid to an Olympus E-510 DSLR, which I start to like more and more. The life preview, also in 7x and 10x digital zoom, works acceptably well also in UV.

My favorate target was used again, that nice Rudbeckia flower which is known to sport some sharp UV pattern. Plus this time also UV fluorescence will be tested out.

As light source a 375nm UV LED was used here and no other modifications were done, not even an filter was used. Here now the UV shot using the Baader 2" U-filter, just color balanced to taste, no other modifications done.

The second shot I used the same UV LED, but the filter used was the Baader UV/IR Cut filter, to suppress UV.

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

More info on this very interesting field may be found on my site