Capture the Incredible Using the Photo Trap and High Speed Flash

by | June 25, 2008

© Joe McDonaldOn the last day of our six week high-speed flash hummingbird photography shoots in southern Arizona, I shot 20 gigabytes of these marvelous birds in flight. We were leaving the next day for the three day drive back home to Pennsylvania, and I was busy packing the truck with the assorted flashes, Bogen supports and Mary’s cooking paraphernalia. I knew this packing would occupy most of my day but the temptation of getting just one more great shot, one more unique pose, was too much for me to ignore. With that hope I kept one of our hummer sets going while I did my Rubik’s Cube puzzle of packing the truck.

Hummingbird © Joe McDonald

While I had a lot of throw-aways, I also had a lot of keepers while I spent my day packing!

You might be asking yourself, how could he do both? How could he shoot hummers and pack a truck at the same time? How, too, could I get a good night’s sleep and still capture exciting images of Ringtail Cats or Gray Fox, or photograph bats skimming across a pond while I’m sitting a hundred feet away, enjoying the night sounds of the Arizona desert while sipping a cool one?

How have I been able to catch images of wasps and bumblebees in flight, of leaping treefrogs and tropical geckos, of striking rattlesnakes and running Basilisk Lizards, of gliding Sugar Gliders and flying squirrels and jumping chipmunks, or flying owls, bluebirds, wrens, and swallows? Easy, and all with the aid of just one tool, the Photo Trap!

The Photo Trap is a device for firing a remote or unmanned camera, or tripping a flash. It allows you to capture action that would be virtually impossible to obtain using traditional methods, or by relying on your own reaction time. Instead, by wiring a camera to the Photo Trap, this tripping mechanism does the work for you.

Photo Trap © Joe McDonald

The Photo Trap, with the camera connection and arming device to keep the camera “awake” and ready to fire.On the left are the infrared sensors, both transmitter and receiver, attached by a Velcro pad.

Like some of the infomercials you may have seen, the Photo Trap is not available in stores, but it is available directly from its inventor, Bill Forbes. That may be why the Photo Trap isn’t as widely known as it should be, and why fewer photographers use it than obviously would if they saw it in a catalog or a retail store. That’s been a plus for those photographers smart enough to own one, because the images they’re capturing are quite unique. If Bill weren’t a good friend, I’d probably be keeping the secret of the Photo Trap to myself right now, but it is truly too good a product not to share.

Laser area © Joe McDonald

I’ve added in the red line representing the laser, which would be invisible except for a red dot at the target area. This is perfect for catching small subjects like flying insects.

Laser system © Joe McDonald

Illustrated is a laser system, requiring the transmitter and receiver to be opposite each other, and the infrared transmitter, which works in all three of the methods described here.

Over the years the Photo Trap has evolved from a somewhat large, toolbox-sized unit into the present model self-contained within a small, 4x11x11 inch plastic case. The Photo Trap can be used to trigger a camera, a flash, or even a video camera, although I’ve never used it for the latter. In most applications, it does so by means of either an infrared sensor or a laser sensor.

I used the compact current model for most of my work in Arizona this spring, using the infrared sensors to fire my camera. This model offers the option of three different camera-firing methods. This option is extremely important, because depending upon the subject one method may work more efficiently than another. Let me explain those differences and their potential uses.

Method One

Infrared works by a circuit being triggered either when an infrared beam is broken (we’ll call it the “break beam” mode), or when a beam that is interrupted by an object in the beam’s path is once again “connected” (we’ll call it “make beam” mode). Several previously available infrared-tripping devices also worked in this fashion, and all required the transmitter be placed opposite a reflector, essentially aimed in a straight line. In the Photo Trap these pieces, the transmitter and receiver, are comprised of two similar looking, small plug-like boxes. The camera (or the flash if the Photo Trap is wired to it) fires either when something passes through the beam, thus interrupting it or breaking the beam, or the Photo Trap fires when something that was breaking the beam moves and the infrared beam is now “seen” by the receiver (the make beam mode). I’ve used the first mode (break beam) often, but I don’t recall ever having the need or opportunity to use the second mode, make beam.

Method One

The make beam mode might be useful if you had a large subject—I’m thinking of a sitting bullfrog—that is blocking the beam from hitting the receiver and is still enough so that the beams can be properly positioned. When the frog leaps, the receiver would see the infrared beam and the Photo Trap would fire the camera or flash. That seems easy enough, but placing beams to do just that may be a bit harder than it seems.

However, the break beam mode is pretty straight-forward and easy to use. The transmitter and the receiver are positioned so that something will move into the beam, thus breaking it and consequently firing the camera. Imagine placing the transmitter on one side of a burrow entrance, for example, and positioning the receiver on the opposite side. When the woodchuck, chipmunk, Black-footed Ferret, or whatever, pops out of the burrow the camera fires!

This method can also be used for birds in flight, especially for rather consistent flight paths like a bird flying in to a feeder or a nest box. Tom Vezo is very successful at this and gives you some insight [see Tom’s article]. However, this method has flaws for this type of application. You might find it difficult to position both transmitter and a receiver out of your camera view. Or, you might find that your subject attempts to go around the devices rather than flying between them. Or you might discover that your bird enjoys perching upon one or the other before flying further! There’s got to be a better way, and there is, as I’ll explain shortly.

But first, let me point out the other frustrating aspect of a break beam function, and that is that your subject could potentially break the beam right at the transmitter or right at the receiver. Since I’m presuming you’ll probably want both the transmitter and the receiver out of your field of view, your lens will be aimed at the middle area of the beam. If your subject passes too close to either the transmitter or the receiver you’ll either have a mis-framed shot or miss the target all together. This happened to me quite frequently when I was attempting to photograph a Sugar Glider, an Australian marsupial that is a flying squirrel look-alike. The glider would often climb up one of my light stands and sit on top of either the transmitter or the receiver, firing the camera uselessly!

This problem can be addressed—I’ve certainly had to do so in the past, and if you use other types of camera-tripping devices you would have to do so. Fortunately, with the Photo Trap there is a better way, and that’s the next method I’ll describe.

Method Two

The Photo Trap has an absolutely unique mode that I find incredible. In this mode the subject’s reflectivity actually completes the circuit by bouncing the infrared light back to the receiver. In this way it’s “making” the beam but in a different fashion than that which I outlined when discussing the leaping bullfrog.

Method Two

Here the subject doesn’t have to pass out of the beam to fire the camera but instead its presence, when it enters into the path of the beam, actually bounces light to the sensor. Well, that’s nice, but so what? Here’s the beauty of it. With this method the transmitter and the receiver can be placed at angles to one another, and not in a straight line. Now you can position the transmitter so that it sends off the invisible, infrared beam into airspace, and aim the receiver at the point in space where you anticipate your subject being. If you imagine both the transmitter and the receiver aiming in straight lines but coming from different directions, the point where these two straight lines intersect is where your subject must pass. If the subject passes through the transmitter’s line below the intersection point the receiver probably won’t detect the reflection and will not fire. Likewise, if the subject passes through the line of sight of the receiver, but either below or above the point of intersection, the system isn’t triggered either.

That’s how I shot 20 gigabytes of hummingbirds while I packed my truck at the end of our hummingbird shoot! I positioned my flashes so that they were aimed at a point in space where an X formed from the lines of sight of the transmitter and the receiver. I positioned this X a couple of inches in front of the hummingbird feeder’s tube so that I’d catch birds flying into or backing away from the feeder, and I’d thus avoid the monotonous bird-with-its-beak-in-the-feeder shots. This also conserved shots, because not every bird that hit the feeder tripped my beams since some missed the X.Had the X been positioned at the feeder I’d have quadrupled the number of shots since none of the birds would have missed the beam.

Although I’m referring to this technique as a crossing of beams in an X, that’s really not entirely accurate. The beam is really shaped like a V or an L, since the point of intersection (the base of the V or the right angle bend in the L) is where the subject is positioned, so that the subject itself acts as the reflector and bounces the infrared light back to the receiver. Some of you may be familiar with other models of camera trippers like the Dalebeam, Shutterbeam, or the WaveSensor, which did in fact work in an X pattern if two devices were wired in series together. This, of course, required purchasing two units—something you avoid doing with the Photo Trap as this is the only tripping device commercially available where one unit works just like a X beam system that would normally require using two units!

Method Three

The Photo Trap’s ability to use the reflectivity of your subject can be employed in a third method, which works similarly to the one just described. In this technique the transmitter and receiver are placed next to each other, an easy task since a Velcro band is affixed to the two units for just this reason. When a subject passes through the infrared beam its body reflects the infrared light back to the sensor, which fires the camera or flash.

Method Three

In Method Three, the infrared transmitter and receiver are aligned together via the included Velcro pads, and aimed toward the area you hope the subject will pass. Like Method Two, the subject reflects the beam back to the receiver to trigger the camera or flash. However, the beam only extends out to about 5 feet or so, so backgrounds won’t affect or misfire the system.

When I used a Photo Trap for the first time I was elated by this feature, since it negated the need to have a reflector (or receiver) opposite the infrared beam. Previously, with other types of camera-tripping devices I had to place a reflector opposite the transmitter, which often constricted the airspace available for my subject to pass through.

For example, in the past I did a lot of work with our bluebirds flying toward their nest boxes, where I placed a transmitter on one side of the flight path and the reflector on the other. My bluebird had to fly through this invisible line through space defined by the transmitter and the reflector, yet I had to position either the reflector or transmitter in such a way that it was not within my field of view. However, the further apart the transmitter and receiver are from one another, the greater the chance that the bird might fly outside the field of view of my lens, yet still trip the camera by breaking a beam. This was frustrating, and presented all sorts of positioning problems that could be addressed, but not without some difficulty.

The Photo Trap’s third tripping method eliminates that problem. Now, if I’m trying to photograph a bluebird, House Wren, or tree swallow flying into one of our nest boxes, or if I’m capturing the mid-leap of a chipmunk, gray squirrel, or flying squirrel I can simply place the transmitter and receiver below my target area, and aim the devices straight up toward the sky. Since this method only works if a subject is within five or six feet of the transmitter I don’t have to worry about leaves high in the treetops overhead tripping the camera by accident.

Ringtail cat © Joe McDonald

I used Method Three for this Ringtail Cat as this proved the simplest way to position a transmitter and receiver without interfering with the movements of my subject.

On my recent hummingbird photo shoot in Arizona I employed this third method to photograph nocturnal mammals that visited a water set that I had erected. The key to this type of work is controlling the direction from which a subject passes, so I had a rather elaborate series of wood baffles and ramps that guided Ringtail Cats, Gray Foxes, and two different skunk species straight toward the spot where I had focused my lens. On one side of this water set I left a narrow gap where my transmitter/receivers were aimed, and these units were placed far enough back that the beam itself didn’t reach the opposite side of the water set where logs or wooden baffles may have reflected the infrared beam back and misfired the camera.

The Photo Trap can also be tripped by sound, with a microphone attached to the system, or by a pressure-pad. I haven’t found a nature photography application for myself for tripping the system with sound, although I’ve done industrial-style photography of bullets, bursting balloons, light bulbs, water-filled bottles, and other subjects where the explosion or implosion tripped the system.

The Photo Trap can be wired either directly to a camera or to a flash, and will trip either one. Almost all of the nature photography I’ve done with a Photo Trap has involved having the Photo Trap hard-wired to the camera and not to a flash. Wiring the Photo Trap to the camera presents a problem you will have to address and that’s camera lag time, the time it takes for all the pieces of this photographic puzzle to come together. When a subject breaks the beam or otherwise trips the Photo Trap, a circuit is tripped and an electrical signal travels to the camera. That’s virtually instantaneous, and that’s precisely what happens when the Photo Trap is hard-wired to a flash. As soon as the impulse reaches the flash, it fires, and there’s virtually no visible delay. Unfortunately there is a delay with a camera, and that’s the time it takes for the camera’s mirror to flip up and for the shutter to open. This delay ranges from about 1/10th of a second with some cameras to approximately 1/50th second with most models. A moving object can travel pretty far during that period! I’ve done the math, and a bird flying through a beam may fly almost 10 inches in the time it takes for the camera to react.

How do you handle that? Well, back in the good ol’ film days, I used a Canon 1N RS camera that had a pellicle, or two-way, mirror which cut this time lag considerably down to about 1/180th second. Cameras with lenses that had leaf-shutters, like a Hassleblad, also had faster response times, and some friends bought expensive and generally fragile external leaf-shutters that screwed into the front of their lenses to reduce the lag time.

Unfortunately, Canon doesn’t have a digital equivalent of the RS film camera, and last I heard they had no plans to make one. That’s unfortunate, especially since the light loss with a pellicle mirror can be addressed by using a higher ISO, an easy cure with our modern digital cameras. Without the RS reduced lag time I’m forced to do a work-around, which requires trial and error.

Flying squirrel © Joe McDonald

For this flying squirrel gliding toward the camera I had to anticipate how far the squirrel would ‘fly’ before my camera fired. This is easier to do with subjects traveling parallel to your film or sensor plane, and more challenging for subjects moving perpendicular to that plane.

This work-around simply requires me to focus at the spot where I think my subject will be when the camera finally fires. That “simply” may or may not be a simple solution, depending upon the subject’s speed and position in the frame. Fast subjects will travel further, and those flying straight at the camera pose greater difficulties for achieving focus. If the subject is traveling across the frame, focus may not change from the point when the subject breaks the beam to the point when the camera fires. However, if the subject is flying towards you, you’ll have to estimate how far that distance is, and focus at that point in space.

That is extremely difficult to do on the first try.Fortunately with digital the test trials won’t cost you money, but they will definitely cost you shooting opportunities. You may have to tweak the focus several times until you get the distance right. As I write this, I’ve just begun a setup involving Barn Swallows flying towards the camera, and I suspect I’ll see this article in print before I have it definitively nailed.

Barn swallow © Joe McDonald

In the text above I predicted this article would appear before I captured the definitive barn swallow image but I was wrong, for in the two weeks involved in writing and publishing I’ve now shot about 100 “keepers,” true testament to the efficiency of the Photo Trap.

Lag time is virtually eliminated if your electronic flash is wired to the Photo Trap, since none of the mechanical delays described above are involved. But to use flash your camera must be on Bulb so that the shutter is open when the flash fires. Unfortunately, if your camera is on Bulb, ambient light, even on a dark night, could eventually register on your sensor and create a ghost image. Once, in Texas, I tried to get around my camera’s lag time by manually tripping the shutter, set on Bulb, a few seconds before a Barn Owl flew back into its nest box. I soon discovered that the owl sometimes circled the box before flying inside, and if my shutter were open for more than a few seconds, any distant light, from oil fields or towns, or even a bright moonlit sky, would begin to register. I decided it was a lot easier to just figure out a lag time!

Just as a fast computer and a good word processing program may make one’s writing easier, neither one is responsible for the magic or beauty or inanity of one’s writing. It’s the person behind the keyboard pounding out letters that makes the final production, and that’s just as true with the Photo Trap. In many shooting situations I’m using flash, not natural light, and in these the final image is as dependent upon my effective use of flash as it is my use of the Photo Trap.

Right now, as I continue my barn swallow project, I have two Bogen Autopoles, four Bogen light stands, and eight Bogen Articulated Arms with SuperClamps arranged to position my flashes and the Photo Trap’s beam, plus six electronic flashes to illuminate the swallows and a background. In my studio I’m working on flying insects, too, and there I’m using five flashes, and seven Bogen Articulated Arms and two Wimberley Plamps to accommodate all the picture puzzle pieces. In Arizona, for that hummer setup I mentioned, six Bogen Magic Arms were used, and four flashes. Of course, not every subject involves as much hardware, especially if I can get the results I need by using natural light alone.

Often, however, one can’t use natural light, because the fast shutter speed needed to stop a flying bird or insect requires an aperture that’s too large, and depth of field suffers. Changing the ISO to a higher number could address that, but at the risk of inducing noise. With flash, I can use a flash duration of around 1/8000th and still use an aperture of f16-22, with an ISO of 200. To me, that’s the best of all worlds, so I’ll put up with the heavy hardware requirements.

The Photo Trap can also be used as a “lightning trigger” to fire a camera when the sensor detects a flash of lightning. Lightning up to about 15 miles away trips the sensor, provided the sensor is aimed in the general direction of the lightning strike. The sensor’s coverage is approximately 120 degrees, which is an advantage over some other lightning triggers that are so sensitive that a lightning strike behind the camera may trigger the system. Because there is a lag time involved, it is possible your camera may fire after the lightning strike, and you’ll miss the strike. There’s little you can do about that except have some comfort in knowing that most strikes are actually a double blast, going to earth and back sky-ward, or vice versa, so your camera may react faster enough to catch the second pulse.

The Photo Trap can also be used as a remote camera-firing device since the “lightning trigger” function will also detect an electronic flash aimed in its direction up to about 150 feet away. This can be very useful for cameras set in remote positions, like a favorite perch or a burrow entrance, where a hard-wired system would be impractical. Of course, there are remote camera-firing devices, like the Pocket Wizard, but having a Photo Trap may eliminate the need for owning one and, in truth, I rarely have the need for this type of gadget in my photography. Hence it’s nice to have one unit that basically covers all my needs, however rarely some of those may arise.

I’ve been using remote camera-tripping devices since the early 1980’s, and because of this I have a body of work of seldom-seen, rarely photographed behaviors ranging from striking rattlesnakes to flying owls, jumping geckos to hopping mice. The Photo Trap has replaced all my former tripping devices, and has become an invaluable tool in my photography. If capturing the unique appeals to you, you simply can’t go wrong in getting a Photo Trap!

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