We discuss various photography techniques and DIY lighting circuits to make amazing light paintings.
BUILD TIME: 2 HOURS
DIFFICULTY RATING: Intermediate
Photography can be a fun hobby even if you aren’t very good at it and you are never intending to produce a photo worth publishing. I fall firmly into that category, but it doesn’t stop me trying, having fun, and spending too much on equipment and lenses. And, if you’re not familiar with photography with anything other than your phone, the basics are covered and there are even some phones that are up to the job.
One of my biggest fascinations in recent years has been light painting. Starting out with coloured filters over a speedlight. Things quickly progressed when I noticed several very hard-to-explain photos on a forum, which looked like they involved LEDs. The overall mechanism, however, remained a mystery. In trying to find out, many other ideas surfaced, too.
What follows in this article is several experiments in light painting with LEDs which are either replications of the work of others, or ideas that I have developed since. Of course, the ideas from others will be credited, where I have been able to find the originator.
THE FUNDAMENTALS OF LIGHT PAINTING
Light painting almost invariably takes place in low light or darkness conditions. There are two reasons for this. The first is that the lights that are used for painting need to stand out from what is around them, which is rarely possible in bright conditions. The second is that generally, the lights have to move to have an effect. Assuming that readers may have never touched anything other than auto mode on their phone camera, the way to capture the movement of light is with a long exposure. Experienced photographers can largely skip over the next few headings. However, if you have plenty of experience but none of it has been in the dark, you may still find something useful here.
Exposure is the summary term for a bunch of factors that go into how much light a camera’s sensor gathers for a given shot. When referring to ‘long exposure’, the term really refers to shutter speed. On film cameras and on digital SLR (Single Lens Reflex) cameras until the advent of mirrorless cameras, there is a physical shutter in front of the sensor. At the beginning of the shot, it opens, and at the end of the shot, it closes. The shutter is often two shutters, and on fast shots, one may be closing before the other has finished opening. See the ‘Further Information’ section for a great Slow Mo guys video showing this. On mirrorless cameras, the sensor is exposed to light all the time, and the shutter speed magic happens by careful control of when data from the sensor is recorded and when it is not, so the effect is the same.
In normal, everyday exposures, shutter speeds are in the hundredths to thousandths of a second. The SLR that these photos were shot on has a fastest speed of 1/8000th of a second. However, when there is not as much light, the shutter must stay open longer. In very low light, the exposure can be seconds or more. It is not unusual for artistic shots to have an exposure of minutes, although many SLRs have a built-in exposure time limit of thirty seconds, and after that, a cable release or remote timer has to be used.
The good news for phone users is that many modern phones have an array of modes and settings that can be controlled. I’m a little out of date and use a Samsung Galaxy Note 9, a phone which I bought partly on the basis of its camera. Some phones have manual modes where shutter speed and the other parameters listed below can be manually controlled, or at least pseudo-modified. That means that long exposures are, to a degree, possible on the right phone.
The correct shutter speed for a given photo depends on other factors, but think first and foremost about how long you need to capture the movement you want to capture. If the spool of string takes five seconds to unwind for the spiral photos ahead, there’s no use using a two-second exposure. In other circumstances, your shutter speed will need to be longer than the movement time in order to gather enough background light to make a shot. This is particularly true of outdoor night time landscapes which you are painting in.
All camera lenses, and many modern phone lenses, have a diaphragm inside which opens or closes to regulate the amount of light passing through. It is shown as a number beginning with ‘f’, and many phones have some control over this. In the phone cases, it will be smallish numbers like f5.6, and there may only be two or three choices. On an SLR, mirrorless, or some good compact cameras, the range is much bigger. The smaller the number, the bigger the opening. So, on my Sigma Art Series 18-35mm lens used to shoot some of these shots, the smallest f-number is f1.8, and that corresponds to a very open aperture. The diaphragm is barely involved at all. On the other hand, an aperture of f32 has the diaphragm so closed that the hole for light to pass is almost in the pinhole range.
In low light, letting more light in is a compromise. Big apertures (that’s the diaphragm open, so a small f-number) lets in lots of light but they also have a side effect. The bigger the aperture (the smaller the f-number) the shallower the depth of field. Depth of Field is the term used to describe the amount of the photo that is in focus. A shallow depth of field may mean that only the subject is in focus, with everything else out of focus by varying degrees. That might be ok for a portrait but generally, any landscape photographer will want a lot of depth of field, so that the hills in the distance are in focus as much as the grass in the foreground.
What aperture suits you will depend on what and how you’re photographing. Many light painting shots are taken with other features involved, such as a room full of objects or an outdoor landscape.The latter may be a garden with everything close to the shot, or a full lookout with the painting subject in the foreground and the view stretching away. The great thing about digital photography is that you can experiment until you get it right.
Another factor that affects light gathering is sensitivity. This used to be labelled and recorded in ‘ASA’ in film days, and still is because film is still around and still has niche popularity. In digital cameras, it is measured in ‘ISO’. The lower the ISO, the less sensitive the camera is to light. The higher the ISO, the more the camera responds to a given light level. While it might be tempting to just push the ISO as high as you can, there are two problems. The first is the time issue again. If the camera sensor is too sensitive, the light required will be gathered in too short a time frame to be useful. The other catch is that the higher the ISO, the more ‘grainy’ the shot can be, and the more colour is affected. How much so depends on the quality and age of the camera.
The Nikon D7100 used for these is a reasonably old camera now, and struggles beyond around 1600 ISO. I have found the best colour results and clarity when shooting at night come from 100 ISO with this camera. Yours may be wildly different. This does mean I’ve had some fairly long exposures where other people I’ve been shooting with had much shorter times, but I find that to be a very small penalty most of the time. Keep in mind that you can use very high ISO and put up with graininess and lack of colour, in order to quickly check composition and focus.
Besides a camera, the main piece of equipment you’ll need for taking long exposure photos is a tripod. Even someone with steady hands has a degree of movement and muscle twitch. While you may have never noticed this in general use, you certainly will with an exposure of multiple seconds.
Tripods vary significantly. Some are desktop models meant to hold phones and other small cameras, while others are big and bulk, and meant to hold professional video cameras like the ones you sometimes see news crews with. For a digital SLR or similar, you’ll need one that has a fairly solid structure, so that vibration is not introduced through flex or even wind movement. If you are using a phone or a small camera, a desktop tripod might be enough. Even outdoors in many environments, you can find somewhere to perch one. Don’t use a tree, however, unless there is absolutely zero wind: Even a slight breeze will move a tree enough to blur the shot. If you are shooting with a phone, brackets are available which screw onto a standard camera tripod and hold the phone either on a two-axis adjustable mount or a ball mount.
Exposing for light painting really is a matter of experimentation. The deciding factor may be your painting light source, or the rest of the shot. For example, in one experiment we performed, the background was bright enough that the LEDs had to be on-axis to the camera in order to stand out: The amount of light coming from them could not compete with the brightly lit beachside retail and dining strip in the background. At an ISO and aperture that showed a decent amount of light from the LEDs, we only had as a 1.3 second exposure. That’s not long enough for what we want to do.
By contrast, in a landscape shot with only moonlight and little to no human light sources (besides the ones we’re using), the exposure will have to be long enough to capture a defined background, and aperture and ISO can be used to make sure the LEDs are not too bright. This is the perfect situation for having multiple light paintings in one shot. That could be by moving apparatus, or by using different types. In such low light, you can move around the shot operating, triggering, and moving light mechanisms and devices, and remain invisible in the finished product. As long as you don’t stay in one spot long, you’ll be indistinguishable in the final shot.
Because of the array of hardware, painting options, and environments to try light painting photography in, there are no rules. There are sound guidelines explained above regarding exposure and settings, but even then, different people will have different experiences. The only real rules come from the balance between your source of light for painting, and the sources of light otherwise in the photo. This could be moonlight, city lights, or flashgun/speedlight sourced. The only option is to play, and work out your own rules, which work for you, your equipment, and your locations.
Some of the simplest devices I have seen for light painting are handheld battery/LED combinations. Some of these are as simple as a coin cell wedged into the leads of an LED. Others are AA batteries in holders with a resistor. LED light sticks work well, as do some small lanterns. Anything that emits a reasonable but not excessive amount of light, and can be moved easily, is viable.
To explore, I used a small grain of wheat incandescent globe on a 2xAA battery pack, which gives a unique warm light colour and is far less sensitive to its direction to the camera than 5mm LEDs with a defined viewing angle. This was inspired by existing artwork, but I was unable to find the identity of the original artist, so I won’t go into detail. The shot was older and the caption described that a small torch with its reflector head screwed off had been used.
I also tried 5mm LEDs with the 2xAA battery packs as well. LEDs do not have enough internal resistance to current-limit themselves and will burn out even if the supply current is matched perfectly. Modern LEDs are quite resistant to this and an LED designed to last 100 000 hours may still last 5000. However, it's sound practice to use a resistor, so I added a 10Ω LED in series, and a header socket to be able to swap different coloured LEDs in and out.
To shoot these effects, it’s just a matter of experimentation. For some shots, I held onto the battery back and moved around. For other shots, I tossed it through the air and caught it, then repeated. Having a friend here helps expand the possibilities. Black photographic backdrops are available fairly cheaply if you don’t need studio quality, but I used a black sheet from Kmart, washed enough times that it wasn’t shiny or reflective anymore. The good thing about shooting in total darkness or near enough means that you can have as long an exposure as you like.
This idea also does the rounds of the photography enthusiast social media, galleries, and forums. Again, it was very hard to find an originator, so rather than credit the wrong person, I’ll just say that I didn’t come up with this idea. I did modify it, however. The spiral is achieved by having a coiled string or line with a light on the end, and allowing it to unwind as it falls toward the ground. This involves having it on some sort of spool. Many online examples use an empty cable reel, fishing reel, or similar improvised shape. Usually, they’re hung from a height.
I decided to modify this idea by making my own spool that could be hung from a height or sat atop a stake, so that it could be used anywhere that an overhead suspension point was not available. I turned to 3D printing for this, and the files will be on the DIYODE website for download. The centre of the spool has a 20mm hole, which should fit many tomato stakes or other garden stakes. If yours is narrower, like a bamboo stake, then wrapping the top in PVC tape should be enough to bulk it out. You could add your own 3D-printed reducer, too. On top is a ring, through which an s-hook or any other suspension method can be passed.
The light source for this is a 3V coin cell. As noted before, there really should be a resistor here, and I added a 10Ω one again, as well as the socket from before. This time, however, I tried something different: A colour-changing LED. These are often used for mood lighting and are a standard 5mm LED case with three dies and a controller IC inside. There is one die each for red, green, and blue. Most of the colour sequencing ICs built into these LEDs have a slow change between colours, with combinations of colours included. Some fade between colours, others fade to black then fade to the next colour.
However, early experiments showed that the transition was often too slow to really capture much change. Enter Jaycar Electronics, who stock two models of colour-changing 5mm LED. The older one is the standard slow variety, but the newest, ZD0269, has no fade. It flashes between colours, and quite quickly, too. This was perfect for my test, and is the one you can see in the photos.
In addition to all of this, the plan did not turn out in reality. I tried the cable reel and 3D printed versions, and found that the weight of the light was not enough to make the string unwind. I added a AAA battery taped on for weight, and this produced better results. They were not perfect, however, and the photos show a tendency for the light to unwind and drop irregularly, and not spiral outwards as much as other people have achieved.
To help solve this, I tried light duty hookup wire, which helped a lot. Using a camera remote control is very useful in this design, and giving the battery/light source a little shove helps get a much better spiral effect.
This idea may well not be original, but I haven’t seen it elsewhere. In thinking about how a spiral would look in reverse, I tried to come up with a way to make the string wrap around the stake and thus get shorter, but the dynamics were hard to control. It had to move fast to make centrifugal force do its thing, and getting the right vertical travel was nearly impossible.
Initially, I thought of using a spindle with a line attached, with the light source at the end. I wanted to use a pull-string to spin the unit, so that the light on the line would spin, and swing outwards under centrifugal force as it got faster. I 3D printed a form to do this with, designed to sit on the top of a garden stake.
Because of the significant weather event that drowned the East Coast of Australia toward the end of March, I lost a lot of time to try this outdoors before we went to print. When I did get a gap, the unit was a total failure. On investigation, there was too much friction between the stake and the socket in the 3D printed tool, and as the unit cammed over when the string was pulled, it did not rotate.
A redesign lead to the current arrangement. This is similar but now has a bearing involved to that rotation is guaranteed. This solved the problem in bench testing but I had to take the test photographs indoors, with a studio lighting tripod instead of the thin black garden stake normally called for. In addition, I ended up dumping the string to hold the light, and using firm wire instead. In this way, the arm swings outward when the unit rotates.
Further thinking resulted in a plan to use electronics to solve the problem. While increasing success with the manual version led me to keep going that way and not pressure a motorsied one, my ideas might prompt other people to have a go.
I envisaged a servo with an arm mounted with the LED on the end. The arm would rotate from vertical, pointed down, to horizontal, pointed sideways. Using an Arduino Nano or the like would mean the LED could be controlled to turn on when the servo started and off when it stopped, and limit switches could control the end limits. If you're feeling really adventurous, try a servo for rotation as well. All parameters can them be customised to control the shapes made.
Perhaps the most impressive of all the LED-based light painting apparatus I have seen is one which appears to have captivated light painting enthusiasts for years before its creator laid claim to it and showed how it was done. Originally, photos began to be posted anonymously or under pseudonyms, showing amazing domes of light with no visible centre. Some were close-ups, others landscapes or cityscapes with multiple domes in them. Others were in bushland areas with coloured flash lighting or ambient light.
While it is impossible to know for sure, no one has, as far as I can find, challenged the claim to this invention that was later made by Andrew Whyte. He deserves full credit and I have not significantly modified this idea. At the end of the article, in ‘Further Reading’, there is a link to his tutorial page. His other light painting is worth a good look, too.
THE DOME CONSTRUCTION
The dome is built on a bike wheel. This does involve not being able to ride the bike, as the centre bearing (or rather, what was the bearing) is used. This means you can’t ride around and make these patterns on the go. It is a surprisingly simple design. A rod is passed through the centre and secured, or attached to the outside if the wheel is not of a construction that supports using the centre. This rod should be the same length as the radius of the circle, so that the wheel sits at a 45° angle when resting.
The bike wheels I used here were borrowed, and arrived with the bearings already disassembled, so I can’t show you that process. If you want this to be permanent, try finding a bike on a hard rubbish/curbside pickup, because it’s not worth buying a wheel. I was unable to find wheels for cheaper bikes like the toy store and sport store variety. Wheels on their own seem to only be around for serious bikes, and are seriously priced as well.
In either case, I decided to make a 3D-printed assembly to hold the bike wheel, so I could adjust the radius on the fly. This was just a cylinder which has a hole the diameter of the shaft, and room for the head of an M3 cap screw. This was mounted in a nut embedded in the plastic, and on the other end, a wing nut and standard nut were used to lock together, forming a thumb screw. This clamps down on the shaft, and fixes it in place at whatever diameter I choose.
DOMES WITH FIXED LEDs
Around the outside of the wheel is fixed a string of LEDs. In most of the original posts, these are fixed-colour lights, the better to keep the method a secret and watch the frenzy of people trying to replicate it. Andrew has since used multicolour LEDs, but I still wanted to explore with fixed LEDs. What I ended up with are two different string lights from a local hardware store. One has flash patterns but the individual lights are fixed colours. The other is just fixed light. I started with the latter, wrapping the light around the outside of the wheel. The battery pack goes in the middle of the wheel, just taped on.
The other light string was originally solar, and runs on a single AA battery. I measured the output, wondering if there was a boost converter somewhere in the largely unmarked circuitry, but no. The lights are only fed 1.2V. I tried them briefly on a 1.5 volt AA, but got no light at all. On soldering them back onto the circuit, they light fine. On a whim, I pressed the mode button to make them flash, and measured the output voltage - an unfluctuating 1.2V. This implied that there is some form of addressing going on within the sealed LEDs, and that meant using the inbuilt controller. Instead, I converted this string to run on a single AA battery. The battery simply replaces the Ni-Cd rechargeable that was there, and the solar panel is disconnected.
DOMES WITH ADDRESSABLE LEDs
I had wanted to try changing LEDs, and settled on a USB-powered RGB strip light. Because of the diameter of the wheel, I needed two of these. These have a controller on the end, and can be set to fade between colours, or show a fixed colour, among other modes. In this way, I could choose multiple colours for different domes in one shot.
That was the plan, anyway. It turns out the controller on these, in order to have only three buttons, is very awkward to use in a hurry. If you can get your hands on a remote controlled version, that would work much better.
In all of these dome cases, turning the lights on and off fast enough is critical. You can see in the photos of my attempts that sometimes I'm visible in the shot, having stood still and fiddled too long. That goes particularly for the USB variety, which turn on and off by being plugged in and unplugged. The fixed lights weren't a lot better.
The next day, I tried the lights that were originally solar. These have a very easy to use on/off button, with no other functions unlike the other lights. Because of the lack of weather window, this was done indoors again but I'm happiest with the results.
The direction many makers will probably want to head in here, and it will be my direction too when I get the chance, is to use WS2812 LEDs and make a remote-controlled dome device. This could be preset so that every time the lights are turned off then on again, the colour changes. It could be controlled via an IR remote or a radio wireless system like WiFi or Bluetooth.
Regardless, while many of these shots have not worked out anywhere near as good as many that can be seen online, they're our first attempts and we're encouraged enough by the results to keep experimenting.
Of course, this wheel lends itself very well to being run with an Arduino and addressable LEDs. While not part of my skill set, which mainly focuses on discrete and analog electronics, those with the skills could add accelerometers to measure the rotation and change colour, or give interrupted patterns. You might like to motorise the shaft from the ground end, anchoring it to a motor and flat plate and thus raising the ability to use timing instead of an accelerometer to change patterns. These are just some ideas, I’m sure readers will come up with many more.
WHERE TO FROM HERE?
These are just some of many ideas for light painting, and using basic electronics knowledge. Like most art, the possibilities are seemingly endless. There are far more complex options, and many others that are just as simple as these. There are also many, many ways to use each.
I originally found this entire concept with a simple internet search for ‘light painting’. In older times of photographic technology, light painting was only possible with bright lights such as flash guns, with coloured filters. That is what I was looking for, but I’m glad I found this. The ‘Further Reading’ list contains links to some posts where these ideas have been used very creatively, but they are only some of a vast array. Spend some time trying different search terms, and the ideas will flood in.