Stereo Photography. What is Stereo Photography?

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1 What is? If you view an image through a telescope or a long telephoto lens, you will see a two dimensional (2D) image. Look at the same view through a pair of binoculars and you will see a three dimensional (3D) image, with good separation of objects from the background and from one another. This is because the binoculars provide different images, one for each eye. If we capture two separate images (one for each eye) with the camera lenses approximately 70 mm apart we can achieve the same effect. This is approximately the distance between our eyes and is what allows us to judge distances. Stereo photography was used extensively by the Victorians to produce Stereoview Cards. These were very popular among the middle classes, who bought them as souvenirs of their holidays. Above is the type of viewer used to see the 3D images recorded on these cards. The viewer has two lenses which ensures that the left eye only sees the L image and the right eye only sees the R image. Our brain automatically does all the necessary processing to produce the 3D effect. The OWL Stereoscopic Viewer is a modern versions of one of these viewers and is available from the London Stereoscopic Company priced Page 1 of 7

2 Left Leg Right Leg Technique The simplest method of capturing a static scene is to have your weight on your left leg, take a picture then transfer your weight onto our right leg and take a second shot. As you can see from the above picture, this has the effect of moving the camera the desired amount. Other Methods If we have any movement in the image the previous method will not work. We then have to use methods which take two images simultaneously. The first is using traditional Stereo Cameras. Followed by stereo lenses and beam splitters, both of which will fit onto DSLR or Mirrorless cameras. Illustrations of these are options shown on the next 3 pages. Page 2 of 7

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6 How to Create an Anaglyph Image An Anaglyph is a stereo image created to be viewed with Red and Cyan stereo glasses. The Red lens must be over your Left eye. Open the Right image in Photoshop CC and Save As Any Name.psd. Open the Left image, select all and copy. Paste this as a new layer into Any Name.psd, name the new layer Left (Red). Rename the Background Layer Right (Cyan). Right Click on the Left Layer, Chose Blending Options, Uncheck the G and B boxes (to make Red) and click OK Page 6 of 7

7 Right Click on the Right Layer, Chose Blending Options, Uncheck the R box (to make Cyan) and click OK To counteract the darkening effect that the colour channel adjustments produce I add a new adjustment layer at this point. Layer > New Adjustment Layer > Levels Name it Lighten one stop, Mode = Screen, Opacity = 35%, click OK Make sure this is your top layer. Create a horizontal guide line (View > New Guide > Horizontal > OK) and drag this to a salient point in the image. Use the move tool and the up and down arrow keys to align the two layers vertically. The red and cyan layers should be visible to allow you to do this. Otherwise it may be necessary to temporarily reduce the opacity of the Left layer, to achieve this. Remember to put the opacity back to 100% after vertical alignment. With your 3D glasses on, click onto one of the layers (L or R) and use the move tool and the left and right arrow keys to fine tune the relative positions to maximise the 3D effect. Finally, crop the image to remove any areas where the two layers do not fully overlap. Save the psd file. Flatten the image and save as a jpg. View the final image using your 3D glasses. How Far Apart Should My Images be Taken? The stereo cameras were made with their lenses set about 70 mm apart (the distance our eyes are set in our sculls). It is best to position the dominant foreground element of your image about 3 m away from the camera. If you are creating a stereo image with the dominant foreground element much further away from the camera, you can increase the distance between the two images. Experiment with distances up to 1 m apart. This is called hyper-stereo. If you wish to create close up stereo images it is possible to put static subjects on a turntable, take one shot, then rotate the turntable 3 to 4 degrees and take your second shot. If you have any problems with any of the above, then please give me a call : or Page 7 of 7