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UltravioletPhotography

Dipton Mill woods


Jim Lloyd

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I was going to start a thread on "The UV photograph as contemporary art", but then thought that sounded a bit grandiose. I have been studying art for a while now and still don't really feel any wiser. Except maybe that its one word, but means many different things and that's fine, although people can get hung up on worrying about what the word means. Anyway, I guess I just mean that after all the technical stuff it ight be nice to think along other lines for a bit.

 

Here are a few from today

 

Nikon D3220 full spectrum conversion

Soligor 35 mm f/3.5 - f11

Asa 200

Exposure 1-4 seconds

WB in Lightroom using custom camera calibration file - then quite a bit of other adjustment - dehaze, saturation ++

 

Also put together into a slide show here

 

post-175-0-59960100-1516902549.jpg

 

post-175-0-26178200-1516902599.jpg

 

post-175-0-11044800-1516903190.jpg

post-175-0-82344800-1516902638.jpg

post-175-0-52955300-1516902688.jpg

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These look promising! The frosty false-blue and false-dark green (or green-yellow, whichever) help distinguish the masses. So you have worked up a nice false colour "look".

I like the first and last ones.

I'm wondering if there is a way to bring out the path (coming in from the left) in the 2nd-to-last?

 

*******

 

"The UV photograph as contemporary art"

 

Along those lines, I don't know (yet) of any current, published critical writings about reflected UV photography as an art form. But then I can't say that I keep up much with critical writings in photography in general. The vocabulary required to absorb such writings is a bit tedious to me.

And if there are any currently galleried art photographers having reflected UV photography shown by a dealer, I don't know of them either.

 

Our own Bjørn Birna, who is a serious practitioner of UV photography as art, may have had some of his UV art work shown. I know more about his documentary work, of course. And Klaus Schmitt has had a couple of nice exhibits in Germany for his UV floral signature work. It is likely that some of our UV portraitists have had some work shown, too. [if I leave anyone out, kindly forgive me for not remembering every post we have had here on UVP which might have mentioned having work shown somewhere!]

 

Most everyone here enjoys the technical or docmentary side of UV photography with only occasional forays into more artistic forms. We do get some lovely series occasionally from our members as you have no doubt seen.

 

So, hey, why not write something about the UV phtoograph as contemporary art!! Try it out here first!! Later you can polish it up and get it print-published somewhere. B) B) B)

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Hi Andrea

 

Thanks for your comments - I'll keep working on these.

 

Maybe a separate thread for examples of UV photography as art would be good? Of course no one agrees on what is art and where any boundaries are, but I think if the maker says its art - then it is. I think it depends on the context - some images may be in two camps at the same time. The only contemporary artist I know of working outside the visible range is Richard Mosse - but there are many others I am sure (noted the ones you mention). Be interested to hear of them .

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Hi Jim. I like that next to last image you posted - it has some 'direction', leading me to wonder where it is heading. Could you share which filter you were using for these shots?

 

Also, I like your comment: "...if the maker says its art - then it is". I'm a maker, and I'm about to post some art! (albeit, technical art ;)).

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Hi Mark

 

Been talking about filters so much in previous post (sorry not sure how to reference it here - called "My first Uv photo") and then completely forgot to mention here! - UG1 2mm + BG40 2 mm

 

Playing around with that image - discovered channel swapping - Red/blue here and some other messing about ...

 

post-175-0-43567200-1516924760.jpg

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Jim, Seems like too much blue. Do you have a raw of any of these posted online? Would like to white balance one if you do.

It is all up to your own taste, but frankly these don't look like pure white balanced UV shots to me.

The blue and/or red may look nice, and that is OK, but they don't look accurately white balanced for UV to me.

So if you have a raw available for one of these, then I would like to give it a try.

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Hi Steve,

 

Many thanks for your thoughts. I can't really decide what I should be aiming for with UV white balance anyway. The blue was a deliberate choice, although I am not sure if it's right. I would be interested to see what you (or anyone else) would do. Here the raw file for an example from the same series.

"

The example on the left below is what I get with white balance on the white birch bark and then the one to the right is after I have "artistically" nudged this cooler. As we are trying to "visualize the invisible" I am not sure what is right. I have a fanciful notion that I am trying to produce something which is like the extra channel that birds have - which may include a little blue and maybe their perception is towards the blue (and increased saturation). But then today I was thinking that maybe this is nonsense and as we have no way of knowing what their perception might be like - and anyway one person's idea could be just as valid as another person's - therefore it is better to do something objective ...

 

post-175-0-50401300-1516988847.jpg post-175-0-63755000-1516988873.jpg

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There has been quite a lot of discussion on bird and insect vision on the boards here since the beginning. My understanding is that since they see in visible as well as UV, if you want to mimic their vision at the most basic, you have to do some variation of "shifting the spectrum down" with vis green->red channel, vis blue->green channel, and desaturated UV->blue channel. So our false colors don't play a role since you have to put all the UV stuff in one channel. But it's all far far more complicated than that in real life. Just as an example of the issues, I'm not sure how the three channels should be weighted, and I'm sure it's species-dependent anyhow.

 

Anyhow, one point here is that amplifying the false blue color in the UV pic is not the same as having a visual blue channel, since visual blue and UV are totally distinct - Just look at the salmon photo Hornblende just posted!

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Typically to get the "standard" UV white balance for the board, I use a piece of virgin PTFE (Teflon) and snap a photo of it under whatever the light is in the photos I'm about to take, then I white balance off of it in Photo Ninja and copy that WB to each of my pictures.

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Hi Andy - many thanks for that advice regarding WB - I will try that.

 

I should say that I am interested in this as an art/science project - Picasso said that "art was a lie that tells the truth".

 

My thinking was that since there is quite a lot of overlap between bird and human vision, it would be better to focus on the differences. That is why I said above that I wanted something that could resemble "the extra channel" a bird has. I realise that I shouldn't really talk of birds in general as I am sure there is huge species variation.

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Just been playing around and comparing visible and UV images of the same scene. Sorry These two were shot with different cameras from slightly different positions (the visible is nikon d3300 with standard kit lens set at f=35mm)

 

post-175-0-79043800-1517002572.jpg post-175-0-55384300-1517002628.jpg

 

I did try fiddling with the visible image to make it look like the UV one, but with little success (which is a relief, otherwise I would have wasted a lot of money!). What did occur to me though was that the difference is not just in the different spectral quality at each pixel, but the way the UV light is scattered. I think this is why the tree trunks on the right appear less in shadow on the UV image? Not sure about that, but I think it might be a factor in the different appearance.

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Hey Jim, I also just had a look at your RAW file example. It appears that your green channel has most of the detail, with the red channel being even less detailed than the blue. I guess this is a result from the Soligor lens you are using. And perhaps it is a result from the overall combination of lens, filters, and light source. I'm not sure at the moment what the implication may be as far as you might be concerned, just something to keep in mind as you work out your shooting method/style. (Note: I also see this per channel variation in my own usual setup, though practically only noticeable in the red channel).
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Forests can be tough subjects to photograph; they can have a lot of unruly detail which can distract from or otherwise spoil a shot. I respect your efforts in this direction. I do like the BGR presentation you showed in post #5 better, as I think it looks more natural; but that is my preference, and yours may be otherwise.
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Thanks all for your comments

 

I like your image, Steve

 

To be honest thinking about this is now beginning to "do my head in" ! There are too many variables going on at once - Light source / subject / lens / camera / filter / human eye and brain

 

I have been trying to find out more about the camera sensor part of this chain (maybe this should go in a separate post?). The sensors (or rather overlying filters) are designed to mimic human cone response, and response in the UV (and IR) is just accidental. I have tried searching and I haven't been able to find much on this and most spectral response graphs stop at 400 nm or just a little below. Here is one I found going down to 300 nm, but I don't know if this is anything like my camera (Nikon D3200). I guess it's very broadly right. That is, one would expect response in the blue channel for the longest wavelength UV due to the shoulder of the visible UV peak dropping down into the UV. Most examples I have seen then have something of a small second peak to the red channel in the UV. Not sure why this would be? And I think green usually has the lowest response - possibly rather UV wavelength independent? Does this sound about right?

 

Anyway, this has made me think that whatever colour we get in the UV image is completely spurious (not sure if that's the right word) and an accident of the design of the Bayer filters for visible light?

 

I was wondering if swapping R and B channels could have some logic as then cooler colours in the image would equate to short UV wavelengths and warmer colours to longer UV wavelengths. Or maybe this is nonsense?

 

Sometimes I have found in art that it is actually useful to have some decisions taken away from you (this is something I really like about using film) - So I was wondering is there an official standard for UV photography - maybe in a particular application (forensics). It might be interesting to apply that standard then to a different field (i.e.nature photography)

 

Here is the above scene in BGR for what its worth. I also changed the hue of the R slightly as otherwise the image looked too much like those that can be used for 3D vision. Actually, I can't decide about this, I think I may prefer something more like Steve's example, but this is worth experimenting with I think. In the end I think the choice will depend a lot on the final context of the work. And I forgot the other element in the chain above - that is the history of photography and viewer's knowledge, and the influence of this on the viewer's perception.

 

Sorry if this seems a bit off-beam, but there is a lot to learn!

 

post-175-0-56419800-1517060338.jpg

 

PS - getting close to my global upload limit - I guess I will have to delete some of my earlier images soon?

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Andrea can up your limit but make sure you are using JPG 6-8 or so. I typically use 6, except for LWIR imagery, which is best as PNG.

 

Regarding white balance, we have our local standard which I already mentioned is to use virgin Teflon. Most Bayer dyes seem to be pretty similar, so that has worked out fairly well. Some members swap R/B channels but most do not. I prefer not to, but that’s me. ;)

 

Whether the colors we get in our photos are related to wavelength seems confirmed beyond doubt to me, but the exact nature of that relationship has been argued on this site since the beginning. Very clearly it is not a 1-1 relationship. Beyond that we can’t say much without argument.

 

 

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Regarding the white balance matter: as I understand it, the standardized Teflon or Spectralon test targets are necessary for scientific specimen shots, wherein there must be an exact, quantitative record of the hue of a particular surface. For general landscape work, this is not necessary; you will learn from experience that there are a number of things which have very little chromaticity in the near UV: snow, water foam, many metals, clouds, fog, some stone surfaces, and so on. You can perform your white balancing on these surfaces with fairly consistent results. And there are some things that will not work, most notably the majority of white paints.

 

The argument for BGR rendering is that (due to the way camera sensors work) it ends up rendering the longer wavelengths reddish and the shorter wavelengths bluish. This is at least analogous to how our eyes perceive a visible scene. A similar practice has evolved with infrared pictures taken with 720-nm cutoff filters, for the same reason.

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Jim, White balance targets are not needed with landscapes, or really much of anything, if you ask me, unless you are trying to prove something and make it repeatable to the nth degree.

Plain PTFE sheet varies in surface, some are more shiny, some are more rough, but all tend to reflect, shine, and have some level of gloss to them, and this often causes weird problems with white balance.

Even if you sand them down... and especially when they are in direct sun.

Other types of PTFE that are more porous, such as Spectralon are better at keeping a uniform reflection.

However, in so many cases, I get a better white balance, by hunting around in a photo, or by white balancing the entire frame than I do with any kind of 'standard' target.

You don't need anything fancy for doing landscapes and flowers, you basically don't need anything at all.

In most cases you can trust the full frame 'marquess' or a smaller section that represents something neutral in the shot.

Unless you have some really weird off color over exposed section of the shot, then avoid that area of color for white balance.

It is not that unusual to see some overexposed area of turquoise (I saw one of those on one of your shots on the trim of a car door).

 

In general, UV-A images look black and white, and have some blue (not meaning actual blue light, but blue from the upper UV, 380-400nm range via how Bayer sees that),

and yellow from the 350-370nm range (again via UV Bayer-vision).

It is unusual to get green or even gold, but these happen sometimes. Green can be a result of yellow and blue mix, and generally not from the 340nm range unless the blue range is suppressed.

Below is a UV-A breakdown of colors as the Bayer sees them through a bandpass array, and/or grating.

 

Clark likes to swap his red/blue channels with UV shots. One of the only people I have seen usually do that with UV, and I like his results.

Personally, I tend to like the straight white balance.

You can do anything you want.

 

post-87-0-41572400-1517110065.jpg

 

post-87-0-29283700-1517111440.jpg

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Eh, the Teflon seems to give me better results than WBing off random objects, although I do that occasionally. Using the sidewalk is something I do if I don’t have my Teflon with me. You don’t have to want scientific quality shots to want to have colors that look more or less untinted and often there is nothing in the scene that makes a good white balance target.
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@Cadmium: Thanks for sharing those diffraction grating images - such a straight forward way to compare lens / filter performance! I wish I had those to consult for some of the hardware I have before I made the purchases. Just out of curiosity, would you happen to have an entire library of diffraction grating images for every lens, lens/filter combination out there? (just kidding, but if you do have others it would be interesting to see - in a separate thread, of course).
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Steve, you can even do more with those refraction pictures.

 

E.g. you can average the picture along the y-axis. A simple procedure to do this with PS is just scaling the picture down to 1 pixel size in y-direction and then scale it up again.

 

Then, instead of doing this with the whole picture, you can cut out the central part or e.g. the upper part run this averaging.

I did this with your first one:

 

complete:

post-21-0-59962800-1517155908.jpg

 

 

center part only:

post-21-0-88863000-1517155931.jpg

 

and about upper third without the assumed overexposed area:

post-21-0-90227600-1517155948.jpg

 

As an additional step before doing this, one could select an area without overexposure by using RawDigger.

 

@Jim: Very nice start! I wonder, when cutting away the sky in your pictures, they might become a bit more mysterious?

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@Cadmium

I am wrong or does it look like the Baader-U leaks a lot of Blue/violet than the U-360 + BG40 stack?

 

@Andy

I think I can see the ionized Calcium lines on Cadmium's image!

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@Mark, I did a few others, but only processed a few, just to test the idea out and compare it to the bandpass method (Sparticle).

I trend to like the Sparticle method, just because it is easier, and delineates more precisely, and doesn't really color, but a Sparticle is certainly more expensive to make.

I think I sent Andrea a grating filter like I make for the examples above, so maybe she will try that sometime.

 

@Alaun, Thanks for the tip and demonstration. I will try that next time.

 

@ Hornblende, I think Baader U filters vary some, so some may have a little more blue than others, but my guess what we are seeing here is some kind of artifact of the dichroic nature of that filter,

especially given that the process of these grating shots involves an angle to the light which can do some weird things with dichroic filters.

 

Overall, I was just trying to show the UV colors seen by the Bayer, and maybe what to expect from UV photos in general.

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