Thursday, February 24, 2011

Flourescent Lilly using UV LED torch

Here a result of some fluorescence study using that wonderful Lilly flower I had used before.

Light source was a UV LED torch.

[click on image to see a larger one]




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, February 22, 2011

[IR ev. UV] Makario found a way to use the D7000 at high ISO

I had reported ealier about that problem that IR and UV images will be spoiled through that built in shutter control unit for modern Nikon DSLRs (D3, D3x, D3s, D700, D7000) here on my BLOG.

Now there is good news on the D7000!

I got the info today that Optic MAKARIO in Germany found a way to modify a Nikon D7000 in such a way, that the spoiling of the image through that built in shutter control IR LED system at high ISO / long exposure times will be suppressed. ISO 800 and 1600 are now possible to use with very good results. The effect still exists but in much lower amounts, so at very long exposure times and very high ISO settings it will still be visible though.

This was tested out good, I was told, for shooting IR and my personal assumption would be, that this can be applied for UV work, too.


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

P.S.: (as of July 2011) lifepixel.com now offers conversions for D7000 in the US which also overcomes that problem and allows high ISO and long exposure times without fogged images!

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Monday, February 21, 2011

[UV] Lilly "retro style" using UV-Sonnar 105mm and Polaroid film

Today a leap back in time. Let's dig out the old photo gear and see what could be done with that. Let's go retro!!

So I grabbed my Hasselblad 500C/M, my UV-Sonnar 4.3/105mm, that special Schott UG11 UV transmission filter that came with that rare lens, a Polaroid back and some Polaroid 100 bw film (good till 1987, just "a little" outdated I have to admit). Exposure was ISO80, 1/125, f8 using a 400Ws Xenon flash.

[click on image to see a larger one]




Considering the effort and hit rate, I know now how spoiled I am shooting digital!! Same done digital 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

White Lilly - a surprising lens find for UV and VIS w/o focus shift II

Well, a while ago I was doing these "Psychedelic Lilly" test shots here . Prior to that I had taken UV transmission tests of that very interesting lens family, which turned out to be very promising, reaching down to about 320nm (-3EV). Here now more about that.


These macro shots were done at f8, ISO400, 1/160s using Xenon flash, exposure adjusted using flash power control and ND filters. UV shots were done using the Baader-U filter.

[click on image to see a larger one]

Here now a VIS-UV differential:


quite a sharp lens with quite good UV transmission and hardly any focus shift, as the two overlaid images nearly perfectly match!

Here the VIS shot:


and the UV shot:


Finally now the VIS-IR differential:


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

[UV] EL-Nikkor 80mm for UV - old vs. new type

As I was testing (again) lenses for UV photography, I had done spectrometric tests on Nikon EL-Nikkor enlarger lenses. The question arose, if the newer 80mm EL-Nikkor has as good an UV transmission as the older, full metal type. So now since I found a new one, here the comparison transmission graph old metal one vs new plastic "tyre like" version. Both are f5.6/80mm.

[click on image to see a larger one]

UV transmission graph:


In terms of UV transmission, quite a substantial difference of about one stop in favor of the old type I would say. The newer one seems to have some fancy new multicoating, which brings the transmission losses in the visual range substantially down, but the UV transmission has been quite reduced by doing so.

P.S.: the 80mm EL-Nikkor (the older, chrome black full metal type) has an adapter ring on its base with outer M39x26tpi screw mount (Leica enlarger mount). Beneath it is a M25 thread for older #00 shutters. Company Schneider Optics offers adapter rings, if that one should be missing (oder code 92-013251).
P.P.S.: the filter thread of that older EL-Nikkor 80mm is 34.5mm, which is pretty uncommon, ask me if you need an adapter ring.

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, February 20, 2011

ZEISS contest "Light is my Language" : made 5th place

Just out of curiosity and since the title “Light is my Language” matched the intentions of my work, I had submitted this photo at flickr to the Zeiss contest gallery here HERE. I had shot this image using a rare and razor sharp ZEISS UV-Planar 4/60mm.

[click on image to see it larger]



The contest has been closed and I was informed that my image made it no. 5!

Honestly that was quite surprising for me, as I had never thought that such "exotic work" would make it that far.

So thanks to the ZEISS Jury and to everyone who has supported me, appreciate 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

Thursday, February 17, 2011

CERCO f4.1/94mm UV-VIS-NIR lens test

Well, I recently bought that CERCO f4.1/94mm UV-VIS-NIR lens made by SODERN in France (type 2085). It is no longer available on stock (but on special order from 10 onwards) and has been superseded by the faster 2.8/100mm type 2178. Manufacturer site is linked here.

Here a few tests I made with this surprisingly little, but well made lens. It has a built in double helicoid, which works very smoothly and makes close focusing possible. The front filter thread is non-standard, so I have to have an adapter made for it later. Indeed the rear Nikon-F mount does not allow to attach it to a Nikon camera for infinity shooting, as it protrudes to deep inside. For closer shots it works however or used via adapter on different cameras.

So here a few test results. First the transmission of that lens, which is surprisingly much better than expected and also what is given by the manufacturer. [Measuring the transmission of lenses is not trivial and it took me a while to get that right...]

[click on image to see a larger one]

Here the spectral transmission, also with Baader-U filter attached to it (and Baader-U filter alone)



Sodern claims that they have applied an optimised multicoating for 220-480nm which indeed has a positive impact and gains more than 10% in transmission in the UV range. [please note that my spectral measurements are reliable from about 310nm onwards]

Now some photographic results ...

Infinity

Tests have been done on a dull and overcast day, no direct sun. At infinity shot wide open, it lacks quite some contrast, but shows quite some high resolution. Stopping down (it has no click stops nor markings), contrast enhances as does resolution - BUT stopping down too much produces a very prominent VIS hotspot. I haven't located that effect in UV strangely enough.

VIS stopped down (ca f8):


VIS stopped down full (ca f16) - hotspot:


UV using Baader-U filter, stopped down (ca f8):


Differential VIS-UV shows very little focus shift:


Comparison VIS (left) and UV (right) in bw (gamma/contrast adjusted):


and the same zoomed in:


That lens has obviously not been designed for infinity work, but for closeup.

Closeup

Under controlled lighting conditions, that lens is a decent performer and shows no hotspot issues for closeup work (until now).

VIS stopped down (ca f5.6):


UV using Baader-U filter, stopped down (ca f5.6):


Differential VIS-UV (shows little shift, but that was me holding the UV filter!)


Images straight from the camera, uncropped. Quite nice I have to say...

More testing has to be done of course...


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, February 11, 2011

Filter glass requirements for camera modification

Modification of a camera dedicated to IR or UV needs the replacement of the internal cut filter in front of the camera sensor by a suitable glass filter of similar quality but different spectral transmission.

The challenge with a filter in front of a sensor is, that it has to meet high requirements:

- optically exactly parallel polished
- bubble and inclusion free
- streak and striae free

This very hard to meet since off the shelf filter glass does not provide that usually, as it does not matter in front of a lens - but in front of a sensor (i.e. about in focus), all that gets visible in your image.

A good converter checks his filter glass under a microscope, locates the needed size which fulfills the a.m. requirements and then cuts that small out from a larger piece.

Personally I would rather buy such a filter precut from a professional camera converter, as he would be liable for the quality and not try risky experiments since "cheap is way to expensive" in the end.

An example borrowed, showing a bubble in SCHOTT IR filter glass:


(c)MaxMax

Example for striae in glass:





(c) glassphotonics


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, February 9, 2011

New shutter control unit seems to spoil UV + IR images for modified cameras

Bad news for us UV or IR shooters: It seems that Nikon has introduced for their newest DSLRs (D3, D3x, D3s, D700, D7000) an intelligent "shutter control unit" using an IR emitting LED / photodiode which tells the camera exactly the time a shutter needs to open an close, regulates that if necessary and if to far outside that permissable zone, sends an error message to the camera display asking for service. A very good idea to extend the lifespan of these shutters which are supposed to live longer than 150.000 actuations.

Here now how the D700 shutter and control unit looks like (red arrow points to that shutter control unit):
and here on a D3S:


(c) Nikon Corporation

If now the internal cut filter (which usually cuts from 400-700nm and certainly perfectly blocks such IR radiation emitted by that internal control unit) is being replaced by a clear quartz glass window for UV and/or IR photography, which usually allows a 300-1100nm transmission, this internal IR radiation seems to lead at higher ISO settings to fogging of the resulting images, rendering them virtually useless. At base ISO this effect is not noticeable, but for instance at ISO800 and 4 sec exposure, it gets quite noticeable, as this image shows (shots without lens, lens, camera cap on, viewfinder closed) :
(c) Andrea G Blum

Further tests which have been performed by carefully masking the sensor with black tape and shooting again at identical as above and other higher ISO / longer exposure settings yields a perfectly black image without any signs of such IR fogging/contamination, proving the assumptions.

All this has been investigated, tested extensively and is still being discussed at nikongear.com also looking for a possible remedy, which has not been found yet.

The first reaction of professional camera converters to these findings came from lifepixel.com which since a few days (Feb 2011) now have a warning on their site (quote):

* Nikon D700, D7000, D3, D3x, D3s - These models make use of Nikon's new infrared self-diagnostic shutter monitor circuitry. This function involved an internal infrared LED emitter/detector chip that could fog images. In most cases it will not be an issue unless you shoot in overcast weather using higher ISO and/or longer exposures. We are working on a workaround solution but in the mean time it may be best to choose a different model or maintain base ISO and faster shutter speeds when shooting. (c) lifepixel.com

Optik Makario in Germany also has a warning on his site now.

It can only be hoped that other camera converters will pick up the news and appropriately inform their clientele about that, so as to avoid disappointments.

TO MAKE THINGS VERY CLEAR: A normal off-the-shelf such mentioned camera, unaltered, WILL NOT SHOW THIS BEHAVIOUR and will give perfect images for normal light photography! Only if the internal cut filter is removed or replaced (which also leads to loss of warranty) AND ONLY IF YOU SHOOT HIGH ISO AND LONGER EXPOSURE TIMES the above mentioned effect might show up!

All this is only given to prevent possible disappointments of UV / IR shooters, but the author does not take on any liability for the information presented here - please make your own tests to confirm these findings for yourself!

UPDATE as of 2011-02-22:

I got the info today that Optic MAKARIO in Germany found a way to modify a Nikon D7000 in such a way, that the spoiling of the image through that built in shutter control IR LED system at high ISO / long exposure times will be suppressed. ISO 800 and 1600 are now possible to use with very good results. The effect still exists but in much lower amounts, so at very long exposure times and very high ISO settings it will still be visible though. This was tested out good for shooting IR and my personal assumption would be, that this can be applied for UV work, too.

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, February 1, 2011

Psychedelic Lilly - a surprising lens find for UV and VIS w/o focus shift

Well, while I was doing these "Psychedelic Lilly" test shots here and here with quite a few lenses (the winners being the Noflexar 3.5/35mm and the EL-Nikkor 5.6/80mm), I remembered having sitting around a box with some lenses made by a famous, but overlooked lens maker, I got a few years ago from a friend whom I used to do lens testing with. So I took the same setup I had in place with that nice "Stargazer Lilly" and also tested these lenses in visible light, but also in invisible UV. Prior to that I has already taken UV transmission tests, which turned out to be very promising, reaching down to about 320nm (-3EV) - see the following results.

[click on image to see a larger one]


These macro shots were done at f8, ISO400, 1/160s using Xenon flash, exposure adjusted using flash power control and ND filters. UV shots were done using the Baader-U filter. The shots further away were done at sunny winter daylight.

Here now a VIS-UV differential using the best of these lenses:


and yes, quite a nice sharp lens with quite good UV transmission and hardly any focus shift as the two overlaid images nearly perfectly match!

Additionally here the VIS shot:


Now the UV shot:


And finally the IR shot:


Now let's see how that very same lens performs for targets further away. Shots of the roof about 15 meters away on a sunny but cold winter day (ice reflects UV very well).

VIS-UV differential (UV is blue):


Which clearly shows, that also at that distance this lens has hardly any focus shift!

VIS shot:



UV shot:


And here now some quasi infinity shots. Target was that golden globe in the center of the image.

VIS left, right VIS-UV differential (UV is blue):


Here a comparison of VIS (left) and UV (right) in black/white:


Hardly any noticeable focus shift also at that distance! I had feared about a hotspot, but none was visible in my tests so far.

CONCLUSION:

• hardly any UV - VIS focus shift in close up (macro), mid and far distance

• very sharp and contrasty in all tested ranges in UV and VIS

• no hotspot in any ranges in UV and VIS

• [also tested good for IR in close up (macro), but that was no prime interest]

Well, the surprise was a big one, as I also shot comparison shots using my UV-Nikkor and the difference was of course there, but that sharpness, contrast and nearly total lack of focus shift still amazes me, as this lens under test did beat both the Noflexar 3.5/35mm and the 5.6/80mm EL-Nikkor!

I have to research more on that lens, so more will follow on that one 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