High Speed Photography Paper

High Speed Photography
By Matt LaVoie


High speed photography is a type of photography developed to capture moments too fast for human eyes or a regular camera to see.  The techniques of high speed photography are unique because they allow a picture to be taken at an exact, predetermined moment, and because the resulting picture is very clear because of the fast exposure.  Through the use of high speed photography, I have assembled a video of pictures featuring eggs shot by paintballs at different stages in the destruction.  My first success in high speed photography was during the summer of 2007.  Using the Internet to learn the techniques, I managed to get the proper equipment needed to take the pictures I wanted.  By using my digital SLR camera, a flash, and a little wiring, I managed to successfully photograph air-gun pellets going through playing cards.  With a little practice, I was able to figure out how to photograph almost anything.  That is when I decided to make a video of eggs being shot by paintballs.


Eadweard Muybridge is credited with the original development of high speed photography.   He was the man who improved camera technology to take photos of fast moving scenes.  He led the way for other photographers such as Harold Edgerton, Ottomar Anshutz, Étienne-Jules Marey, and Thomas Eakins who took the idea and put their own spin on high speed photography.  These men’s techniques are still similar to what I’m doing today.  Despite improvements in technology, basic concepts have remained constant throughout the last century.  In order to better understand high speed photography, it is best to start from the beginning, with Muybridge, and build from there.


High speed photography originated in California during 1872.  The Governor, Leland Stanford made a $25,000 bet with another wealthy man that a horse has all four feet off the ground at some point during its gallop.  Stanford wanted to prove it scientifically, so he hired photographer Eadweard Muybridge to resolve the question.  Stanford was also a race-horse owner, so he used his own horse, Occident, to be the one photographed.  When Muybridge approached this task, there was one fundamental problem.  Shutter speeds of the time were many times several seconds in duration.  In order to get a properly lit picture, these slow shutter speeds were necessary because technology had not progressed enough to collect light more efficiently.  Photographers of this time period did not use strips of film negatives like are used today.  They used wet plates, also called "amphyitypes", which were glass plates coated with a mixture of albumen, silver nitrate, and water.  These plates had the modern equivalent of an ASA rating below 4.  Combined with the available lenses of the time (about f/32), these extremely slow cameras would need to be helped significantly in order for Muybridge to get his pictures.  If Muybridge attempted to photograph a moving horse with current cameras of the time, the results would be dark, and would most likely only have a ghosted image of the horse streaking across the entire frame.  


Muybridge settled on using Scoville cameras with Dallmeyer of London stereoscopic lenses.  The shutter mechanism was designed by John Isaacs and consisted of an electromagnet connected to a lever, similar to a telegraph key, attached to a shutter.  Twelve such cameras were to be laid out on the track, equally spaced every 27 inches, with thread strung from each camera’s shutter release to the other side of the track.  When the horse ran across the area to be photographed, the series of threads attached to the electromagnets would break, releasing the shutters.  When the thread broke, the battery-powered electromagnets pulled the lever inward, allowing the shutter to be pulled down by two India rubber rings.  20" x 24" stereo wet glass plates were chosen to be used for these pictures.  The technology Muybridge used was not the only thing that could be improved though.  The right environmental conditions could help him too.  The horse that was to be photographed was black, so to make it most visible in the photos he wanted a white background.  Muybridge covered the race track with salt and sand while also putting white, reflective panels behind the track all in order to reflect as much light as possible.  The brighter the background of the picture was, the more light there would be reaching the camera, resulting is shorter shutter speeds needed.  With all this light, he was able to get exposures of about 1/1000th of a second, resulting in clearer pictures than ever before possible in photography.  When he was finished, Muybridge had managed to get a series of twelve pictures, definitively showing that all four feet do leave the ground at once.


Muybridge continued to work with Stanford for ten years, during which he received funding to take pictures of all sorts of subjects.  In 1979 he analyzed animals, from birds to bears, and how they move.  In August 1879, athletes were photographed while fencing, jumping, tumbling, etc. Twenty-four cameras were used for these studies.  In 1882, Muybridge’s career with Stanford ended when Stanford published a book containing photographs by Muybridge without crediting him.  In his lifetime he had accomplished exposure times of 1/6000th of a second and had published hundreds of thousands of photographs.  Few people have accomplished more in the development of photography than he did.  He changed photography from posed portraits and still life, to anything you could imagine.  The photographs I am taking are similar to those taken by Muybridge because the basic concepts at the same.  To get the shortest exposures possible, we need large amounts of light as quick as possible.  Neither of us simply press a shutter button either.  Cameras set up ahead of time, triggered by a device are needed to capture the exact moment in time.  


Today, high speed photography is used by more people for similar reasons.  There is a demand in the industrial environment for high speed photography to analyze the functioning of machine equipment and products.  High speed video is used to find problems that we cannot see.  Video is the newest advancement in high speed photography.  Frame rates of 1000 to 25,000,000 frames per second are now possible with exposures as short as 1/500,000,000 per frame.  These are still being developed however and cost from $10,000-$1,000,000+ per camera, making them impractical for most companies to use.  Individual, high speed photographs are therefore still popular for use in analyzing equipment.  High speed photographs are still taken similarly to Muybridge’s time, but have advanced with technology.  Instead of using thread to set off the shutter, there are a variety of electronic methods.  Sounds triggers are a type of device that listens for a sharp, loud noise.  These are convenient when photographing in a quiet environment and a loud noise signals the event, such as a gun shot.  Light triggers are used in conjunction with a light source such as a laser pointed at them.  The device detects when the beam of light reaching it is broken.  This is useful when photographing something moving that is large enough to break the beam.  Contact/electrical triggers are those which simply have two pieces of metal that make contact when the subject hits them.  If this type of trigger is placed between two colliding objects, the resulting picture will be the exact moment of impact.  All this advancing technology is now falling into the hands of amateurs as computer chips become increasingly better.  Computer technology has led to faster, cheaper, and smaller cameras, triggers, and flashes.  The most important part computers have played in high speed photograph is the digital camera.  It might take hours to get a single, perfectly timed photograph, and the photographer can now have instant feedback as to whether or not he was successful because of built in LCD screens.  If a picture is not successful, then it is possible to know what needs to be fixed immediately, saving many hours.  People do not have to be professional photographers to be part of the knowledge of how to take high speed photographs thanks to the Internet.  High speed photography is now being used for a wide range of purposes from artistic, to informational.


Here, I will go into detail on how exactly I took my photographs of eggs being shot by paintballs.  First, it is important to understand one of the most basic concepts of high speed photography.  An expensive camera is not needed.  Any SRL camera or similar camera with the option of having everything manual is all that is needed.  I use a Canon 350D which is a digital SRL camera.  The trick to high speed photos is to be in a completely dark room.  If there is no light, that means the camera’s shutter can be open for large amounts of time without getting an exposure.  It will not be able to ‘see’ anything.  While the camera’s shutter is open, if an external camera flash is set off, then the brief burst of light it lets out will provide the exposure for the camera.  The amount of time that the light inside the flash is on can therefore be called the exposure time, since the shutter speed means nothing in darkness.  There are several reasons high speed pictures should be taken like this.  Flashes have very short durations of light which can replicate shutter speeds of cameras that would cost tens of thousands of dollars, while providing enough light to fully light a scene on their own.  Also, flashes have no mechanical parts unlike SRL cameras.  They are triggered by electricity, and so there is almost no lag between when it is triggered to when it fires.  Most flashes have light durations of about 1/250th of a second to 1/1000th of a second.  I use a Vivitar 283 flash which was first produced in 1975.  This means that it can now be bought second hand for as low as $30.  In its time however, it was a professional quality flash, with a regular light duration of 1/1000th of a second.  With the turn of a knob, it can be adjusted to 1/32nd output power, which makes the light dimmer, but also much faster.  This flash provides exposures as short as 30 microseconds (millionths of a second).  


So we know how to light the image using short exposures, now we need to trigger the flash at the right time.  This requires some homemade circuits.  Parts and instructions for building an electronic trigger can be bought from the company HiViz, which is how I made by light trigger.  Because high speed photography is not popular enough for companies to mass produce these tools, pre-assembled units are very expensive.  Building one myself cost only about $15.  My light trigger has a small receiver on it that looks like an LED light bulb.  It is used by pointing a laser pointer at it, and whenever the receiver doesn’t detect the light anymore (when the beam is broken by a moving object), it will send an electrical signal to the flash.  This also requires making a slight customization to the wires attaching to the flash.  Using this device, the steps to take a high speed picture are not very complicated.  A dark room is needed, and a laser needs to be pointed right at the light receiver.  While holding the camera shutter open with a remote switch, an object can be dropped into the path of the laser beam, breaking it, and thus setting off the flash.  The camera shutter can then be closed and the resulting picture will be of the exact moment the laser beam was broken.  


Now this technique needs to be applied to shooting eggs with a paintball gun.  In addition to shooting eggs though, I also recreated the scene multiple times, making the flash go off at different points in the destruction of the eggs.  The result was a collection of pictures that could be assembled into a video that roughly shows what it would look like in slow motion.  Because I needed to shoot an egg for each frame of the video, the first challenge was making an environment that could contain the mess.  I constructed a box out of PVC pipe that is 4 feet wide and long and 6 feet tall.  There was a baby pool I had with a 4 foot diameter that fit in the base of this box perfectly.  By hanging black tarps from the top of the box, down to the bottom on the inside of the pool, I had a completely enclosed area that could be hosed out easily.  Next, I built a stand for the egg to rest on using extra PVC pipe, and then a table for the camera and flash to be on by cutting the legs of a plastic shelving unit.  I placed the egg stand inside the box in the middle of the baby pool, and I put the camera/flash table just outside the box.  I cut holes in the hanging tarps so that the camera and flash could see into the box.  This brought another problem.  For the camera to see the egg exploding, it needs to be in plain view of it.  To protect it from getting covered in egg, I used Plexiglas to build a clear box just big enough for the camera to protect it, and then bolted it to the table so that each picture would be framed exactly the same.  Next I needed a place for the paintball gun to be mounted securely because it needed to be aimed before hand so that when the lights were turned off all I’d have to do is pull the trigger.  I used a small, portable table vice that is normally used to hold wood when cutting.  All I did was place the gun in between the clamps and mark where exactly it was so that I could put it in the vice the same way each day I took these photos.  Because I couldn’t adjust the height of the table vice, it became the standard for how high the egg stand and camera tables had to be.  In case a paintball missed the egg or if it just went through it and kept going, I needed a bullet trap to stop it.  I used a plastic milk crate and lined it with old mouse pads and trash bags to absorb the impact of a paintball, and then placed it on the other side of the egg where the gun was pointed.  Holes had to be cut in the hanging tarps for the paintball gun and the bullet trap as well.  The light trigger’s receiver was placed on the floor of the baby pool, behind the base of the egg stand.  The laser pointer was taped onto a tripod (making it easy to aim) that was positioned behind the camera.  It was pointed through the hole the camera was looking at with an angle so that it crossed by the egg and hit the receiver resting on the floor.  


Now, the only thing left to be done was to take the actual pictures.  I double check to make sure the laser is pointed where I want it, and then turn off the lights.  Now the sensitivity knob on the light trigger needs to be adjusted because there is now a greater contrast between the amount of light it sees when the laser is on it and off it, now that the lights in the room are off.  It is now time to shoot the egg.  Because I can’t reach the camera’s shutter button and the gun’s trigger at the same time, I use a remote cord to trigger the camera.  It is also useful to have a camera with a ‘bulb’ exposure setting, meaning that you can hold the shutter open for as long as you’re pressing down the shutter button.  Now, assuming the camera is on and the paintball gun is loaded, all I have to do is hold down the button on the camera’s remote cord, pull the trigger, and release the button.  If I saw a flash go off, then the picture was successful.  To repeat the picture again, but at a different point in time, I just have to move the laser closer or farther from the egg, because the exploding egg crossing the laser beam’s path is what sets the light trigger off.  If I move the laser closer to the egg, it will take a picture close to the time of the impact, if I move it away, it’ll take the picture after the egg has had time to expand a little.  


The hardest part of high speed photography for me is that nobody ever told me any of this.  The internet has information on it, but it is very limited because once people figure it out, they are weary of giving their techniques out to everyone.  Ninety percent of the time I spent on high speed photography, was figuring out how to do it, or what I was doing wrong.  My digital camera was indispensible throughout learning all this because it gave me instant feedback allowing for me to learn by trial and error until I got it right.  When I first started taking high speed photographs, I was thrilled to get a anything at all- quality was not so much of a factor.  Now that I’ve been able to experiment more, I’ve been able to improve.  For example, my first pictures were taken at f/9, ISO 100, at 55mm.  Now I realize I was over exposing the subjects.  For this project, I used f/20, ISO 100, at 28mm.  I chose to change the aperture in order to darken the subject because I was placing the flash so close to it.  It also benefitted the focus of the image because as the egg explodes, it expands not only left and right, but closer and farther from the camera.  f/20 gave me a larger depth of field making it easier to have focused pictures.  I chose to use 28mm because that also gives a larger depth of field, and because the camera had to be placed closer than before in order to look through the hole I cut in the tarps.  ISO 100 is the lowest ISO my camera offers, and gives the best quality images, especially for slow shutter speeds.  These changes reflect the experience I’ve gained from my failed, and successful pictures.  


Photographers like Muybridge not only set the stage for high speed photography, but modern photography as it is today.  However, the advances that were made were not just improvements to photography.  They helped bring the world into a new era with new possibilities.  Muybridge’s work led to the future of movies, and video.  It is often not appreciated just how much some of these people accomplished.  High speed photography is a small genre of photography that, while not very popular, has still made great improvements through history.