Light Painting with Time-Varying Light Sources by Dan Bennett

Light Painting Artist Dan Bennett sees things differently. From an early age he was fascinated with light, specifically time varying light sources. Dan has trained his eyes to see the unseen. On his website and in his book he offers many resources to help others see the light including tutorials on “Eyeball Jiggling” and “Mirror Jiggling”. Check out the full interview, images and videos below.

LPP ∇ Hey Dan your Light Painting work is very interesting can you tell me a little more about yourself and your work with time varying light sources?

DB ∇ My involvement with time-varying light sources goes back a looong way – I started when I was 4 years old! My bedroom had an electric heater in it, which had a neon indicator to show when it was on, and I remember kind of jiggling my head around in the dark and seeing a trace of orange dashes. Of course, at that age I didn’t know that the trace’s dashed appearance was due to the fact that the neon was switching on and off 100 times per second. (This was in the UK – in the US it would have been 120 times per second.)

I went on to develop a technique of moving my eyeballs deliberately so I could see the rapid time-varying behavior of various light sources, and had many years of pleasure doing that. Then in my 40s I decided it was time to write a book about it, and in preparing the book I found out that photographing time-varying lights is easily as much fun as observing them with the naked eye. Plus, it gives one the opportunity to really study the way a light source is varying, especially if its behavior is complex.

Then I found that by choosing the right light sources and moving the camera in the right kind of way, I was producing stunning images that stand up well as light painting art.

LPP ∇ How do you feel your work is different from Light Painting in the traditional sense?

DB ∇ Most light painters create images by doing stuff with lights over a time-scale of maybe 30 seconds to a couple of minutes, sometimes more. My time-scales are shorter – anything from a tenth of a second to 2 or 3 seconds. Whereas most painters use spatial changes in the scene to develop a cumulative time story which becomes the image, I take advantage of the fact that the lights I’m shooting are themselves changing very rapidly. My images are a “convolution” of the lights’ behavior and the motion of the camera.

Most light painters will be familiar with LED sources which leave high resolution dashed traces in the image – it’s a side-effect of the type of technology used in the LEDs, and maybe it’s regarded as a cool effect. You’ll see it if you wave a pixelstick too fast, for example. In my case, it’s this variation that is the source of my images. I simply move the camera and let the lights’ intricate time-varying activities paint the textures and features. After all, it’s much easier to shake yo’ camera than it is to wave a row of street lights around in front of a camera on a tripod!

Super quick tutorial: Set the camera to manual, with the shutter speed at, say, 1 second. Focus on the light source, then take the photo while sweeping the camera, or rotating it, or zooming it, or any combination of the three. If the image was too dark or light, change the aperture or the ISO. It’s that simple. 🙂

I remember one night visiting a garden where every tree was festooned in LED Christmas lights. There were people there using tripods and monopods… not me! Whizz! Sweep! Rotate! Zoom! I was having waaay more fun, and getting much cooler photos too!

LPP ∇ What is it about these Time Varying light sources that draws you to them specifically?

DB ∇ So I’d better define what I mean by “time-varying light sources”. I’m talking about lights – usually man-made, but sometimes natural – which are varying in brightness, color and/or pattern very rapidly. Too rapidly to see in normal circumstances. This includes almost every street light: you may think they’re just continuously illuminated, but far from it. They flash 100 or 120 times per second (and there are some LED ones out there that flash over 2000 times per second!). It’s possible to see this behavior with the naked eye – if you keep your eye moving. Here is tutorial on how to use a mirror in the technique of “Mirror Jiggling”

But street lights, though ubiquitous, aren’t the stars of my art images – for that I go to more complex sources such as neon tubes (the real neon, orange-red ones are amazingly complex in the time domain), LED displays (Las Vegas, baby!!!) and other sources. These give rise to the amazingly complex and attractive images you see here.

Since I can use my eyes to see the traces of time-varying lights, I can easily scope out a potential subject by jiggling my eyes for a moment. If I see cool traces, I pull out my camera.

Another aspect of these images is that it’s kinda mind-blowing that it’s so simple to produce such cool photos. Here is tutorial on how to capture the traces in your camera:

LPP ∇ Can you give me some examples of natural time varying light sources?

DB ∇ Twinkling stars can be observed by moving your eyes to see the brightness variations, but since their light’s so dim, it’s not very rewarding. It’s much more rewarding to photograph them! This photo of Sirius, taken by putting a moderate zoom (200mm or so) onto a Canon DSLR and pointing the camera at the star for a 1.6 second exposure while moving the camera in a loopy pattern. This lets us see what the eye can’t: (a) that the twinkling’s happening much faster than you might think (several hundred times per second), and (b) that it’s colored! (The explanation for this is amazing, but I don’t have room for it here.)

LPP ∇ Thats remarkable what are some others?

DB ∇ It’s well-known that lightning often consists of multiple strokes along the same path. This makes a wonderful – and very challenging – target for visual observation (where you have to be moving your eye or a mirror when the lightning happens) or for photography (where you have to be moving the camera). I’m including a lightning photo I took by operating the camera like a machine – sweep click sweep click sweep click – once per second for about two minutes!

Moths flying in the light of car headlights are good to observe. Obviously, the moths aren’t emitting light, but their wings reflect light in a rapid, periodic way which can be easily observed. In fact, you don’t even have to move your eyes, because the moths are moving for you!

LPP ∇ It seems you have a very scientific approach to your light painting work, are you more interested in the science or art side of your work?

DB ∇ Good question. Yes, I deeply enjoy the science and technology side of lighting and vision; being able to explain what I can see or photograph is great. And yes, I also deeply enjoy producing great photos that stimulate the eye and brain. But that actually reveals what my main driving force is: enjoyment. 🙂 My book is all about going out and seeing and photographing time-varying light sources, and opening up a whole new world that’s all around us every night and is easy to see and shoot if only we know how. It’s all about enjoyment.

LPP ∇ What is your background? Did you study photography or science?

DB ∇ I have an degree in electronic engineering, but I’m not really an engineer. I’m definitely a bit of a science head; and I’ve been ramping up my photography skills over the last ten years or so, not just in the time-varying lights area.

LPP ∇ What are some of the ways your work could be used from a scientific standpoint?

DB ∇ Another good question… Actually, since most of my subjects are man-made lights, the people who design and manufacture them already know the technology well, so there’s not too much to add there. However, for people who enjoy seeing stuff and understanding stuff, it’s really cool to see into the minds of the engineers. For example, I can glance at a row of street lights and tell you in what configuration they’re connected to the three phases of the electrical supply.

Or I can glance at the LED tail lights of a car and tell you if there’s just one circuit driving them or multiple circuits, and how they achieve the change from tail light to brake light function.

One really interesting observation I once made by accident was when I saw a drop of water falling from a roof in bright sunlight. I wasn’t even watching it; but being a seasoned observer, I idly noticed that it made a dashed trace on my retinas. Well, usually that means that the light source is flashing, and if it had been a street light, that would have been the end of the story. But it was sunlight. I think we’d know by now if the sun was a pulsar… and it isn’t. 🙂 So what was the explanation? It was simply that the drop wasn’t spherical and was tumbling as it fell, catching the sunlight periodically – multiple times per second. This is a great example of the kind of observations you can make and enjoy if you train yourself.

LPP ∇ Getting a little off Light Painting here but thinking about observing the drop of water falling in sunlight. Do you have an interest in quantum theory and the role of the observer? It seems relevant to me especially related to how the lights are actually on and off but we see them as on, without noticing.

DB ∇ I guess it’s tempting to regard the fact that I saw the flashes of sunlight only by not looking directly at the falling drop, as somehow analogous to quantum theory, which states that as soon as you observe something, you’ve essentially changed it, so you can’t know everything about a system even if you observe it. That’s Heisenberg for you.

Well, that’s not really what’s going on here – the timescales are too long and the sizes of objects are too large for anything quantum to be involved. Let me explain the whole basis of visual (by eye) observation of time-varying lights.

The reason that you can’t see that a street light is flashing 120 times per second is that the cone cells on your retina don’t respond very quickly when a light stimulation finishes. They take a while to be ready to tell the brain, “OK, that light just switched off”. When the light source is pulsing rapidly, the next pulse comes along and restlimulates the cone cell before it ever had the chance to register the dark period between the pulses. That means that it’s essentially always stimulated, and you never see the flashing.

This is useful – engineers design all sorts of lights and displays knowing that they can get away with a flashing light output, because no one will see it. (Interestingly, insects can see it… imagine being an ant under a streetlight!)

However, by moving the eye – or by using a mirror to move the image across the retina – it’s possible to take advantage of the relatively slow response of the retina. Moving the image across the retina allows a fresh group of cone cells to be exposed to the next pulse of the light, and the slow decay of the image (persistence of vision) means that a trace is formed which you can see for long enough to interpret and enjoy. It’s actually a graph of light output vs. time, where the time axis is along the path of the trace. Unlike a camera, which records light on the sensor until the image has been captured and processed, the eye’s trace is transient, lasting maybe a fifth of a second; but it’s definitely enough to see all the things I’ve photographed here.

Of course, if you’re asking how the retina’s cone cells respond to light… well, that’s quantum. 🙂

LPP ∇ One last question, can you tell me a little more about your book and what readers will find inside?

DB ∇ The bulk of the book (A Field Guide To Time-Varying Light Sources) is exactly what it says on the packaging – an ordered presentation of all the different kinds of time-varying lights that are out there, from CRT monitors to twinkling stars, street lights to airplane propellers. (In fact, it’s probably the only book on the planet that validly categorizes “moths” and “pulsars” in the same section!) (Actually, it’s the only book on the planet about the topic of time-varying lights, period.)

The first part of the book covers seeing and photographing these lights, with a chapter devoted to photography. If nothing else, the book will provide explanations for some of the dashed-line artifacts that people might see in their light painted images; but hopefully it will also inspire artists to look for new sources of light in their palettes, and to regard time-variance as a class of visual brushes.

LPP ∇ Thank you Dan for taking the time to answer these questions, its a very interesting subject!

DB ∇ Thank you.