LIGHTPAINTING WITH INFRARED AND ULTRAVIOLET LIGHT
CAN UV AND IR BE CAPTURED IN ONE EXPOSURE?
Yes, you can, as you can see in the picture. However, this is anything but simple. For most people, the question of what this is good for comes to mind immediately. To be honest, I don’t really know at the moment whether we can and will actually use this creatively and seriously in light painting at some point. However, some aspects are very interesting and cannot be implemented with other techniques.
WHAT DO I NEED FOR THIS?
First, I need a camera that can capture as much infrared light as possible. Some time ago I converted my old Nikon D70. You can find the article here: infrared-light-painting. The D70 is also, unlike most modern cameras, quite sensitive to UV light. In normal photos this is rather unintentional, but for our purpose it is exactly what we want.
On ebay you can get a D70 in good condition for 60 – 70€.
You don’t really need a special lens for it. There are special IR and UV or X-ray lenses, but that’s not much use for us because we want to shoot both at the same time. Of course you could change the lenses during the exposure, but we don’t want to exaggerate. Especially since these lenses are not exactly given away. The light painting of the old man (above) I took with a normal lens (Tokina 19-35/3.5).
When the article talks about UV light, it refers to a black light lamp with a certain amount of visible light. Light sources that emit pure, invisible UV light are not known to me and at least not accessible for normal mortal people.
DO I NEED FILTERS FOR THIS? AND IF SO, WHICH ONES?
Well… to the emergency such Light Paintings also work without filter. Since I made the picture above alone it was not so easy for me to screw the filter on or off the lens during the exposure.
Working without a filter is possible if I have a completely dark room available. If I work with infrared light in this room, the camera takes only infrared light.
For the UV part you need even less a filter, at the latest when you have researched the prices for it. A UV-pass filter, that is a filter that only lets UV light through and blocks the rest of the spectrum, costs around 350 €. Yes you read correctly three hundred and fifty euros. And such a filter is not exactly available on every street corner.
During my research on UV photography I didn’t find much anyway. This article brought me a little enlightenment.
An IR filter is quite cheap in comparison. For my 720nm filter I paid 19€. This filter only lets light with wavelengths greater than 720nm pass, all wavelengths below that, visible light, are blocked. So with the help of this filter, I can turn on visible light without a large IR component while light painting with the IR flashlight and not have to work in the dark. Mostly I put a green lamp in the room, the light of the lamp is not visible in the painting. This filter should also be used if the room is not completely dark, i.e. if unwanted light from outside enters.
If we work with visible light in the same image, we use an IR cut filter or rather a UV and IR cut filter. This filter blocks the non-visible UV and IR range. So the D70 without IR cut filter in front of the sensor will not pick up any infrared light. Most LED lamps but also many other light sources have a certain IR portion. This would change the color of the light painting with the visible light, at least in the picture. The brightness of the Light Painting would then possibly also be greater. The number of failed attempts for the image would increase.
UV/IR cut filters from reputable manufacturers are quite expensive, easily in the triple digits for 77 mm thread. For this reason, I have bought from a dealer in China, where something like this costs only about a tenth.
The fantasy prices that are sometimes called for filters are usually unacceptable to me anyway. We are talking about small glass discs with an aluminum thread, which cost a few cents to produce. Even if the friends would coat that with gold and platinum, that still does not explain the price of sometimes several hundred euros.
WHAT LIGHT SOURCES DO I NEED?
In addition to the normal lamps for light painting in the visible spectrum, you need an IR (flashlight) lamp and a UV (tache) lamp. These are quite affordable. When buying one, make sure that especially the IR lamp has the lowest possible power. Don’t buy the thick monster part with 20 watts, that is viiieeeeeel too bright for our purposes. We use a small 5W lamp for 13€. Even this small lamp is brutally bright. For the picture above, I had it attached to a bundle of black fiberglass. With this I illuminated my face from top to bottom as fast as I could. It shouldn’t have taken longer than 0.3 seconds. The set aperture was 8.
WHAT IS SO SPECIAL ABOUT LIGHTPAINTING WITH IR AND UV LIGHT?
Light painting with invisible IR light takes a bit of getting used to, because you can’t see what you’re doing. Above all, you can not estimate the brightness at all, only (many) test shots help.
Light painting with UV light is a bit different. The light of the UV lamp can be seen with the naked eye. You can at least see where you shine the light. However, it is also difficult to judge the brightness, which also works only with test shots. Since the UV flashlight obviously has quite a large amount of visible UV light, I am quite blue in the face.
Using UV and IR light in a single exposure is a challenge. The IR lamp is very bright, unlike our UV lamp. We are talking about 3 to 4 stops of difference.
If there was a way to change the white balance during the exposure, the blue color would disappear from the half of the face with the UV light.
In this picture I used only the UV lamp. The white balance was at the limit, at 25000k. The hepatitis look could certainly be avoided by using less light on the skin.
To prevent the usual red color cast from the IR light part, I set the white balance manually to about 4100k. While this fits quite well with light painting with lamps in the visible color spectrum. Even though the colors may be slightly altered it usually looks like it should be that way.
I have not yet found a reasonable solution for white balance when using IR and UV light at the same time. A subsequent correction via different layers in post processing would be a possibility. However, working in a single exposure without processing on the computer is a very important aspect for me in my light painting images.
Likewise, in a multiple exposure, one could set the white balance correctly for IR and UV respectively.
For now, I think I’ll leave it at the blue faces.
Two exciting aspects come to mind. One is the huge jet-black pupils when people are illuminated with UV light. However, one should not exaggerate with it, the UV light is not good for the unprotected eye.
The second aspect: IR and UV illumination (almost) do not mix. You can see this quite well in the two pictures above. The blue UV light is quite cleanly separated from the monochrome IR light. With colors from the visible light spectrum this is impossible. You quickly get the effect of color banding or the colors mix.
With our light painting experiments with light from the invisible spectrum we are still at the very beginning. There is hardly any information about these topics on the Internet, we have to work out almost everything ourselves in many experiments.
A like-minded person who uses at least IR light regularly in his light paintings is Dan Chick from Denver / USA. Without the exchange with him we probably would have given up already. Thanks for your support and inspiration Dan.
Allways good light wishes