Wondering how to make stereo images? If you’re not familiar with the concept, check out what Wikipedia has to say about it. Described below is my attempt to do interesting portraits using two synced SLR cameras.
Viewing Stereo Images
images are combined using the anaglyph method (using coloured
glasses), since most people have a hard time getting cross-eyed
viewing to work. Also, everyone has a pair of
paper glasses they got from a cereal box or SI Swimsuit issue.
If you don't have any glasses, you can get some cheap paper ones here
or some really good plastic
ones. What you need is red-cyan glasses,
with red on the left eye.
Making 3D Images - A Little Theory
principle of Stereoscopy is to take two pictures that are taken with a slight
horizontal offset. The resulting images are then displayed to a single eye.
The brain does the job of merging the two together in a single image. A good
3D image will trick the viewer into perceiving depth in an otherwise flat
you really intend to make a comfortable and optimized 3D image, you need to
choose the inter-axial distance carefully, as this setting cannot be modified
in post-production. I strongly recommend using a stereoscopic camera
calculator such as the many stereoscopic iPhone apps available, or better yet
the handy and free
spreadsheet found on binocularity.org (which is a pretty amazing website
for 3D photography).
Single Camera Stereoscopy – Fast and Easy
My friend Francois and I wanted to experiment with stereoscopy with digital cameras for a while. Since we worked in 3D and VFX, we did get a chance to do some stereo with computer generated elements. I did try experimenting with a single camera on a sliding plate (such as this really cheap macro rail available on eBay). In this case you just slide the camera left, take a picture, slide it to the right, and take a picture again. What’s really nice about this method is that you can use any inter-axial distance you want (great for macros). Just make sure to lock all settings manually on the camera before taking your shots.
The issue is that I wanted to take pictures of people in motion, and I couldn’t since they moved during the time it took me to slide the camera. Luckily, my friend François happened to own a camera and lenses that matched mine (350D / rebel XT with 50mm f/1.8 and Canon 10-22mm). This meant that we could finally try dual-camera stereo imaging!
challenge was to get the two camera lenses as close to one another as
possible. Typically the distance between human eyes is 65mm, so as a starting
point we usually want to match this distance between lenses to get a
realistic effect at a reasonable distance. In this case we got 100mm of
separation, which gives a great effect but is a bit exaggerated. If you try
to increase the distance between cameras too much, the brain just gives up trying
to reconnect the images.
details of making a remote can be found on the connections
page. In this case I ran wires from the remote plugs on each camera and
connected them to a DPST switch (which is a double pole switch – two switches
in one). The switch connects the tip and the base of the 2.5mm jack – this
triggers the shutters. I then tucked the switch and the wires in an empty
Make sure both cameras have exactly the same settings, all set to manual (the eye is very sensitive to discrepancies between images. This includes WB, saturation, sharpening, everything. We used RAW to avoid any problems, and this affords us a lot more latitude when post-processing the images. If you plan on using flash (see below), use a slow shutter speed to make sure that both shutters stay open until the flash has fired. Also, make sure the date and time matches exactly on both cameras. This will make it a lot easier to join the pairs, as you just need to sort the folder of images by date.
1st Attempt – Available Light
is a test of the original rig, using available light. We quickly realized
that using a 50mm was much better than 10 or 20mm, because at that focal
length, you need to get really close to the subject and the difference
between the points of view is too great for your brain to make the
connection. Here is a
failed example at 10mm.
2nd Attempt – Indoors With Flash
time was much more fruitful. I decided to use some strobes, but the flash
sync was an issue. I got the idea to connect the flash sync to each camera in
series. I made a basic hot shoe adapter. It's quite rudimentary, but it
works. It's made out of two pieces of plastic, nails and a few wires. For
those who don't understand the principle behind a hot shoe, check this out.
Combining the Pictures
this case Photoshop was used; instead of some of the specialized software you
can find on the web (you can also try the free Stereo Photo Maker, which is
great). This provides a lot more latitude, and you can even retouch the final
composite. I was looking for a simpler solution than replacing the red channel
(as is mentioned in most other tutorials). Instead I ended up creating two
layer sets with layer effects to divide the channels. This allows for better
color correction when the shots are combined, and allows for easy conversion
from color anaglyph to black-and-white anaglyph (I'm a stickler for good b+w