Stereoscopic 3-D photography has been around almost as long as photography itself. In the 1830s Sir Charles Wheatstone theorized that we see the world in three dimensions because our eyes are set about 2.5 inches apart, and see from two slightly different viewpoints. You can test this by holding your thumb at arms length. Close one eye and look at your thumb, then look with just the other eye, and you will see that there is a deviation, or parallax, between what your eyes see. Your brain fuses these two views together, interpreting the amounts of parallax as depth. This is called binocular stereopsis.
Wheatstone figured out that two cameras could be placed side-by-side and take simultaneous pictures, creating a pair of photographs from both left eye and right eye perspectives. When viewed through a stereoscope, the left eye only sees the left image, the right eye only sees the right image, and we perceive a single 3-D view.
The author's 3D photos from Comic-Con
Throughout the late 19th and early 20th centuries, stereo photos were all the rage, with many thousands of stereo cards produced. In fact, many Victorian era homes kept a stereoscope as the centerpiece of their living rooms - sort of the entertainment center of the day. Still, the process of making 3-D images was very complicated, as it was necessary to have two synchronized cameras to take the pictures, and quite a bit of skill to align and mount the finished prints or slides for viewing. Over the years, a number of film cameras have been made with dual optics and shutters, specifically for stereography, but these still require a great deal of meticulous work by the photographer in order to properly align pictures for display.
The 21st century has seen a resurgence in the popularity of stereography, or 3D imagery, and thanks to the availability of inexpensive digital cameras and photo-processing software, do-it-yourself 3D imagery is now possible.
The simplest method for taking a 3D photo requires just a single camera, and a stationary subject. Place your feet firmly on the ground, with your weight on your left foot, and take a picture. Shift your weight to your right foot and take a second picture. You now have a stereo pair of images, one for the left eye and one for the right eye, which can be viewed in 3D. Obviously, this technique, called “sidestep” or “cha-cha” 3D, only works for subjects that are not in motion.
To take stereographs of dynamic subjects, we will need to take two photos at exactly the same time. Japanese camera manufacturer Fuji recently released the first digital camera equipped with two lenses for 3D. Of course, for the technologically savvy, you can make your own 3D camera rig using common building materials and two digital cameras.
For this project, we’ll use a pair of matching Canon PowerShot cameras and specialized synchronization software called StereoData Maker, or SDM, which is a nonvolatile firmware upgrade based on CHDK, the Canon Hack Development Kit. SDM adds a set of features to certain Canon cameras, specifically for the taking of 3D pictures.
Aside from the digital cameras and tools, the core components of the rig won't cost you more than $20! Now it's time to assemble the pieces.
First, you will need two Canon PowerShot cameras (they don’t need to be the exact same model) and the corresponding StereoData Maker firmware. While SDM isn’t available for all Canon PowerShot models, it does work on a wide variety. A full compatibility list can be found at the Stereomaker.net website . Scan the list for your cameras and download the specific firmware and common_files.zip for each. Unzip both archives to the same directory.
SDM comes with a simple installer program that will format your SD cards and install the SDM files. Run the sdminste.exe executable, insert one of your SD cards into a card reader on your PC and click “new install.” Select whether this flash card will be for the left or right camera and click OK, then follow the onscreen instructions for formatting. Do the same for the other card. Make sure to note which card is for the left camera and which is for the right.
Slide the physical write-protect tab down on the SD cards and insert each into the proper camera. The firmware only loads from the cards when they are in the “locked” position, but the cameras are still able to write photos to them normally.
The next step is to mount the cameras in a side-by-side orientation. Some hobbyists sell specialized 3D slidebars for two cameras online, but you can make your own. This can be as simple as drilling two holes in a wood ruler and bolting the cameras down with 1/4-inch thumbscrews.
Ideally, you want the lenses of your cameras as close together as possible—about the distance between two human eyes. The best way to do this is with one of the cameras turned upside down. To mount the cameras in this way, we will build something called a z-bar with two right-angle truss clips or braces, which you can buy at any hardware store.
Align the sides of these two bars and fasten them together using heavy cloth tape, leaving the holes along the base exposed. With 1/4-inch thumbscrews, mount a camera onto each clip, using metal washers on each side of the base to make sure you get a tight, level fit. Position the cameras so that the centers of the lenses are as evenly aligned as you can make them. Don’t worry if the alignment isn’t 100 percent perfect, as we can correct the images later in software.
One of the functions added by StereoData Maker is synchronization of the cameras’ shutters via a 5-volt pulse sent through their USB ports. This requires that a battery-powered switch be attached to both cameras via USB cables. The Stereomaker.net website contains several varying schematics for this synch controller circuit.
The simplest to assemble uses a pair of USB connectors with both pins 1 wired to a button, and both pins 4 wired to a negative battery terminal. The batteries’ positive terminal connects to the other contact on the button, so that when it is pressed, it completes the circuit to both cameras. The cameras need to receive a 4.5- to 5-volt pulse, so you can use a combination of three 1.5V AAA batteries.
You can build this circuit into any small enclosure, such as an Altoids tin, which has a hinged lid for easy access. We found female USB connectors, battery holders, soldering supplies, and push-buttons online at Allelectronics.com .
Cut openings into the side of the Altoids tin to fit the two USB ports and glue the ports in place. Drill a hole in the face of the enclosure for the push-button as well. On the battery holder, connect the positive battery wire to one contact on the button switch, and carefully solder the negative battery wire to pin 4 on both USB ports. Solder a short wire from pin 1 on both USB ports to the other contact on the button. You can use the USB cables that are supplied with the cameras to connect them to your synch controller. Alternatively, you can hardwire USB cables to the controller in place of the connectors. If this step seems too daunting, there are links on the StereoData Maker website to sources that sell pre-assembled USB switches.
Once you have the hardware assembled and the StereoData Maker firmware installed onto the SD cards, you are ready to start shooting 3D pictures. Power up both cameras and wait for the SDM splash screen to appear. You can access the SDM menus by briefly pressing the “direct print” button to put the camera into <alt> mode, followed by the menu button.
The SDM menus contain numerous options for both beginners and more advanced stereo photographers. For now, we will just check to ensure that the USB synchronization is turned on. Make sure that any settings you adjust on the left camera are also changed on the right camera. Press the “direct print” button again to exit the SDM menu.
The left photo
You can now set your cameras up as you normally would to take a photo, adjusting the ISO, shutter speed, and aperture identically on both cameras. Press and hold the button on your USB switch to auto-focus. When both cameras are ready, their blue LEDs will light up. Release the USB button and both cameras fire simultaneously, capturing your stereo pair.
A general rule of thumb for taking good 3D photos is that the distance between the rig and your subject should be at least 30 times the distance between your two lenses. In other words, if your lenses, measured from center to center, are 2.5 inches apart, you should be at least 75 inches, or about 6 feet, away from your subject.
The right photo
Now that you have taken a pair of images, it’s time to look at them in 3D. To do this, the two images need to be aligned and put into a format suitable for 3D viewing. While this can be done with general image-processing programs such as Adobe Photoshop, most stereographers prefer a specialized freeware application called StereoPhoto Maker .
Begin by downloading and installing the StereoPhoto Maker program. Remove the SD cards from your cameras and copy the contents onto your PC. We recommend organizing your files into subdirectories for left and right images to make it easier to keep track of them. Run the StereoPhoto Maker program and under the File menu, select “open left/right images.” A dialog box will open, asking for the left image. Browse to the folder with the left photos, select a file, and click Open. Do the same for the right-side image, selecting the corresponding picture from the folder with the right-side images. The program will open both files and show you the two pictures side-by-side.
Under the Adjust menu, select “ auto color adjustment ” to match the tone of the two images. Next, select “ auto alignment ,” and StereoPhoto Maker runs an algorithm that corrects for misalignments between the cameras, and sets the stereo window based on the nearest point in the shot. Once the auto-alignment is finished processing, you can put on your red/cyan 3D glasses, select a color anaglyph mode from the Stereo menu (we prefer Dubois anaglyph , for its color correction), and marvel at the depth in your 3D photo.
If you would like to make more advanced alignments, you can select the easy adjustment mode, and do manual corrections as needed. StereoPhoto Maker will allow you to save your pictures as anaglyphs, parallel, or cross-view pairs, and will even print out a vintage-style stereo card for your Victorian stereoscope.
Stereo Club of Southern California -- The Los Angeles–based 3D club offers 3D tutorials and information on 3D photography on its website.
3-DIY.com -- The author's website on do-it-yourself 3D.