Sunday, July 29, 2007

Olympus E-510 vs. Nikon D70 for UV

I got an Olympus E-510 for a few days and made a quick test tonite with that flower I shot using my D70 a few days ago.

The preview function is quite nice, since it allows quite nice focusing I have to admit. The Ergonomics I had to get used to, quite different that the Nikon.

But all that was not really the subject, I was more interested in the sensitivity for UV; let the result be revealed right now, from my test that would be -4EV as compared to the D70. I also noticed that the tonal range of the E-510 original files (I shot Raw+Jpg simultaneously) is more limited than those of Nikon, but the interesting thing is, that the blue channel of the E-510 seems to be the most UV-sensitive one, whereas it is the red for the D70. The images of the E-510 without any correction look much more "natural", though, since they appear violet/blueish as compared to the very red ones of the D70 [since shooting UV images, a violet/blue tint just feels more "normal" for UV than red images - of course that is nonsense since for humans UV has no "color" at all].

I have developed a process to tone the UV images, so as the tips of the Mexican Zinnia appear in about natural yellow tome, the rest adapts to that (brownish/reddish). Since I used that for the D70 images I adjusted the ones from the E-510 accordingly for easy comparison.

Comparison Summary of Nikon D70 and Olympus E-510 for UV

Target: Mexican Zinnia, ca. 12mm flower head, so the following images are ca. 3x magnification

Lens: UV Rodagon 5.6 / 60mm
Flash: Nikon SB-140 w/o SW-5UV
Filter: Baader 2" U-Filter
- D70: 140mm,
- E-510: 105mm (since the form factor of E-510 is 2, D70 is 1.5)
Left images: Nikon D70
Right images: Olympus E-510 (resized / cropped to D70 size, due to the larger 10Mp format of the E-510; D70 is 6Mp)
- D70: ISO 400, f11
- E-510: ISO 800, f5.6 (there was no other chance to get somewhat normal exposed images)
subjective evaluation: E-510 image still underexposed by -1EV as compared to D70

---> UV sensitivity -4EV as compared to Nikon D70

A shot from that test, first taken with the Olympus E-510:

Now the one using the Nikon D70:

Here now a side-a-side comparison, Nikon on the left, Olympus on the right side:

Oh, and yes, I bought it finally, since liveview makes live esp. for macro shooting much easier even if it doesn't help much for UV or IR....

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

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

Tuesday, July 24, 2007

Can UV light make single cells visible?

A few shots today using the same target (Mexican Zinnia) and the UV Rodagon 60mm. I wanted to see if it would be possible to make indiviual flower cells visible since UV has a much higher resolution than normal white light (about double as compared to green light 546nm).

I also found it quite nice, that this lens performs quite well, even used outside its designed range, here at 3x magnification (design range 1:2...1:20).

Here now some results, first full image reduced to 1024 pics, the rest all 1:1 without compression in size [as usual click on images to see a large image]:

The UV shot indeed reveals quite some detail of the petal structure and yes, the single whiteish spots are individual cells which were made visible:

... and a bit more here:

... and here:

Here now another example using a Vanda coerulea (Blue Vanda orchid) as a target. First a shot using visible light:

This one now in UV, which reveals much more detail:

I find that not only pleasing to see but also interesting from a scientific standpoint that UV light resolves so much more fine detail. This is why UV light is also used in microscopy and to make computer chips. Technology today is down to 248nm and 193nm.

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

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

A multispectral example using Mexican Zinnia

Just a few quick shots today using the UV Rodagon 60mm for multispectral analysis in visual light, UV, UV fluorescence and IR. As usual I used a Nikon D70, SB-140 flash w. SW-5UV filter, UV Rodagon 60mm, Baader 2" U- and UV/IR Cut- filter (for UV and UV fluorescence), B+W 092 filter (for IR).

Target was a Mexican Zinna; the little flower head is about 12mm in diameter, i.e. magnification was about 0.5x which still is within the 
design range of that lens. Here now the visual shot:

The UV shot reveals that special pattern this flower shows:

UV fluorescence shows the intensive light of the pollen:

IR finally looks quite transparent:

Quite interesting how the very same flower appears in different wavebands!

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

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

Thursday, July 19, 2007

A blue sun? How did that come?

So we humans see with our three channels, Blue, Green and Red. UV (less than 400nm) however we can't see [It has been reported that a few people can see UV and funny enough if I look into my spectrophotometer and turn the knob until I don't see any light anymore, it stops at 330nm?!].

So how would we now display shots we have taken with our expensive quartz lens, UV transmitting filter and UV sensitive digital camera? My idea now was to combine the UV and the visual shot into one image, i.e. to remap the UV "color" space into our blue-to-red visual space - we perform a translation so to speak. I usually map UV as violet/dark blue, just because it is at the "right" end of the spectrum, but that is just my personal preference - and it looks good, at least for me.

How that works, you might ask. We take a shot in UV and combine it with a visual shot in a way that we subtract the UV image from the visual shot after some suitable preprocessing, noise removal, sharpening, contrast enhancement - whatever it needs.

An example for that follows now. This shot has been done using some exotic lens, the 500mm focal length Makowsky Katoptaron TS-E 500 mirror only lens. Dr Makowsky developed that lens many years ago in 1968 using only two suitable Zeiss Schott Quartz (Zerodur) mirrors which project light in a Z-folded light path. A side effect of not using any lenses is the ability of that "lens" (optical system would be more correct) to record from UV to deep into the IR region (up to 4000nm as per data sheet).

Here now the visual shot of a sunset from my balcony:

The UV shot however looks very different, like that:
[the "color" you see just respresent the reaction of the built in chip - here a Nikon D70 DSLR - to UV exposure, it is no "real" color...]

So if we now apply the remapping procedure mentioned above, the result is:

So now also the mystery behind my logo has be revealed!

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

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

Wednesday, July 18, 2007

Guess which one has been shot using a quartz lens?

This is a test shot to compare a Fluorite/Quartz lens with a "normal" lens ("X135") for UV photography. The shots show one each per row. All done at f8 and using the new 2" Baader U-filter for the UV shots. The images are cropped/sized for about the same size for comparison. Focus was NOT completely identical, so don't use correct focus as as indicator for your guess, look out more for detail, sharpness & contrast.
[I used Nikon D70 + Baader 2" U-filter + X135 lens. UV shot about -10EV compared to VIS shot, identical postprocessing and resize for same appearance due to different focal length]

And your guess for the quartz lens is which one?

Here are two high resolution images if you click on them:

Some more specific shots with decent UV pattern may be seen here now, first the visible light shot:

and the UV shot:

Details (100% crop), first the visible light shot:

and the UV detail shot:

Oh, nearly forgot, the quartz lens is the first row in the first
two images, the second row is that older X135mm lens, I
calibrated for UV shooting. This was also used for all following
shots. The slight disadvantage is, that you focus in visible
light, flip the Baader U filter in front of the lens, make a
focus adjustment to the UV marker (like that red dot
indicating the IR mark) and shoot. Not such an effort if
you can save quite some bucks...

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

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

On EL Nikkors for UV Photography and a Myth

So on technical aspect today. Lenses for UV photography are not easy to come by, are quite expensive ($.$$$ to $$.$$$) and quite a few people search months and years until they find a Nikon UV Nikkor 105mm, Pentax Ultra Achromatic Takumar 85mm or 300mm, Rodenstock UV Rodagon 60mm, Zeiss UV Planar 60mm of for the medium format photographer the Zeiss Hasselblad UV Sonnar 105mm just to mention a few and truely fully chromatically corrected (i.e. without focus shift UV-VIS). There are still two real UV lenses being manufactured, the Coastal Optics Micro Apo 105mm and the Tochigi Nikon UV 105mm. The interested reader might want to find more on those lenses (images, technical data etc.) on my parallel site under the "special lens" section. (There are some 300 lenses listed in the macro lens
section, but that is another topic...)

So what's the alternative? Enlarger lenses come to mind and some are indeed not that bad. The older full metal type EL Nikkor 3.5/63mm is claimed to be the best for UV since its data sheet mentions that it may be used down to 350nm. So why not run a buch of similar types through my older spectrophotometer and see how they transmit UV? Ideally we would find a lens which
would transmit 300 - 400nm since that is the range a modern camera chip can resolve (like the Nikon D70 and D40 for instance, Canons don't do that at all) and also modern UV transmissive filters pass, like the Baader 2" U-filter.

Not really surprising the fact that indeed the 63mm does 350nm, but also others do quite the same; the 40mm being a real surprise, but due to the short focal length only useable for macro shots and not for infinity or landscape. But UV transmission is not all,
sharpness, contrast and flare (or the lack thereof) are quite important
aspects, too.

More on that technical part later. So here is the outcome of that test as a table (a click on it opens it in larger size). Cut-off wavelength is understood as the -3EV level compared to 100% transmission at 425nm (my subjective setting), so all these are relative values.

BUT be forewarned, all these EL-Nikkor lenses mentioned here, show substantial focus shift when used for UV photography, a fact which usually isn't mentioned but which makes working with them often a try-and-error game. Not really for the serious UV shooter, more a beginners lens to test the waters.

Now if you want an affordeable lens for shooting UV, I have developed a series of useful lenses with quite good UV transmittance and performance. I call them the X-lenses, the X135 being the most used one (f=135mm). A comparison with the UV Nikkor 105mm may be found here. Just do a search for X135 if you want to know more about that one or the X35 (f=35mm, a wide angle for UV) or X90.

Stay tuned on technical aspects, more will follow on that too...

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

On Fluorescence Photography

Taking shots of flowers esp. close up I noticed that pollen seems to somewhat lighten up. So I made a test using a UV flash, but had a UV-blocking filter (Baader UV/IR Cut filter) in front of my taking macro lens. It gets quite obvious, that at least some flowers use the energy in UV light to enhance the brightness of their pollen to make it more visible to insects - their pollinators.

Here some macro shots I did using the 2" Baader-U for the UV shots and 2" Baader UV/IR Cut filter for UV-Fluorescence. The fluorescent pollen get clearly visible.

Some examples for that follow. Here the visual shot first:
(click on images to get larger (1024 pix) images)

The UV shot however looks very different and since the pollen looks quite dark, this means that the UV energy gets absorbed by the pollen. So where does it go to? It gets transformed (maybe just partly) into visual light.

So if we now use the UV cut filter for that African Daisy, this is made visible:

So this is another trick what flowers do to attract pollinators. Here an even closer macro shot of that:

Another example of a multitude of ideas nature has applied.

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

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

Tuesday, July 17, 2007

Ever wondered how Bees might see a flower?

So we humans see three channels, Blue, Green and Red. Bees however can see UV (what we can't), Blue and Green. So if we take a shot in UV and combine it with a visual shot were only the Blue and Green information is used, we can synthesize how Bees see the world - in priciple. The problem is, that we can't see UV so that has to be "translated" into our color space.

Some examples for that follow. This is a well known plant, Bougeanvillea. Here the visual shot first, click on images to see larger files (1024 pix):

The UV shot however looks very different, like that:

So if we now apply the procedure mentioned above, the result is:

Here now another example, a shot just around my house on a path along the road taken this spring. In visual light this looks like that:

And in UV like that:

Bees however will see that (or what I think looks like what Bees see...).

So maybe now we understand a bit more what flowers do to attract pollinators. This is just one example of a multitude of ideas nature has applied.

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

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

[UV] Rudbeckia - a study of lenses for UV photography

This was meant as a simple and unscientific comparison of some lenses for UV photography with focal lengths 50...60mm. All shots Nikon D70 + Baader 2" U-filter + Sb-140 flash @ ISO400, identical postprocessing for all results. Click on images to see larger files (1024 pix).

1) Rodenstock UV-Rodagon f5.6 60mm @f8 [this is the reference lens which has no no focus difference at all, works down to about 300nm, ideal for modern camera chips]:

2) Carl Zeiss Jena UV Objektiv f4 60mm @f8 [trial-and-error to focus, massive focus difference, that is why the image is that large, UV focus is much closer. Works down to 200nm]:

3) UV calibrated old german f2.8 50mm lens (still under development) @f8 [slight focus difference in usual i.e. closer direction, but very sharp and contrasty and useable down to 320nm]:

4) Carl Zeiss S-Planar f4 60mm @f8 [slight focus difference in unusual opposite direction i.e. further away. Quite a surprise that this 300lpm lens also does UV to about 340..350nm, the different color rendition shows the lack of UV transmission]:

5) Tomioka Macro Yashinon f2.8 60mm @f5.6 (due to limited and very narrowband UV response aperture had to be opened one stop) [slight focus difference in usual i.e. closer direction] [This is a non-working example of a modern multicoated lens; many others show the same UV transmission and blueish results; only useable to about 375..380nm which only leaves a useable 10..20nm window, this is why the image is nearly monochrome. Some tweaking might be applied to reach about the same color rendition as with the other lenses, but with substantial efforts] :

6) Steinheil Quarzobjektiv f1.8 50mm @f8 (about, since it uses that old pre WWII aperture setting of f7.7) [strong focus difference in usual i.e. closer direction] [This 1930ish lens is also a noncoated one, so it is sensitive to flare and doesn't have the high contrast modern lenses have...but still surprisingly good. The chance to also use it at f1.8 allows some dream like ethereal UV images. And it does it down to 200nm] :

7) selfmade lens from Quartz Achromat ca. 50mm @f8 (about) [strong focus difference in usual i.e. closer direction; strong abberation and bent field gets visible, but if that is all you have, not bad at all and useful down to 200nm, much more than modern camera chips can handle (ca 300nm)..] :

8 ) Rodagon f4 60mm @f8 [strong focus difference in unusual i.e. further direction. Not bad for an older enlarger lens, useful to about 350nm...]:

9) EL Nikkor f2.8 50mm @f8 [strong focus difference in usual i.e. closer direction. Also not bad at all for this older full metal style enlarger lens; useful to about 350nm...]:

10) D.O. Industries f4.5 50mm @f8 [strong focus difference in usual i.e. closer direction. Surpsingly good and contrasty for that cheap triplet lens; useful down to about 320nm]

This is the visual reference shot [also using the UV Rodagon 60mm]:

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

[UV] How to recover a fainted thermo paper receipt

Reflected UV Photography fascinated me since the first time I read about it on . But it hasn't been used on landscapes and wonderful flowers only, one of the most important aspects was forgery detection an forensics also. Here is some literature on that

Today I made some quick tests with an older fainted 2003 thermo receipt from a gas station. My goal was to get back the fainted information on that receipt using my Nikon D70 @ISO200, Nikon SB-140 flash and an UV Rodagon 60mm lens. The idea was to try out reflected UV, UV fluorescence and reflected IR.

1) UV (Baader U-filter, SB-140+SW5UV):

2) UV+IR (no filter, SB-140+SW5UV):

3) UV Fluorescence (Baader UV/IR cut filter, SB-140+SW5UV):

4) IR (B+W 092 filter, SB-140+SW5UV):

In my opinion the reflected UV and UV fluorescence works quite well, but the IR seems to fail.

The good thing is, that for UV fluorescence one doesn't need an UV transmissive lens (like the one I used), but a "normal lens" suffices. All one needs is an UV blocking filter (like the Baader UV/IR cut filter) plus a strong flash which emits UV. One has to be careful to block unwanted IR, since that might render the results useless (cf #4). So ideally one should have an
UV/IR cut filter in front of the camera lens.

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