Canon Camera, Hackers Manual

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7.7 Stereo photography
213
7.7.1 Stereo photography with a single camera
What works for a chicken can work for us, too. It isn’t really necessary to use
two cameras for creating stereo images. If the subject matter doesn’t
move, you can obtain good results by using a single camera: take the first
shot, move the camera a bit to the right, and take the second shot. This
method is particularly suitable for macro stereo photography. In macro
photography, the shift between the left and the right image must be quite
small—so small that it’s impossible to mount two cameras side by side
without exceeding the optimal distance between the two lens centers.
Shifting a single camera, however, sounds easier than it is. It can be
quite hard to make both images register correctly, especially when shoot-
ing hand-held. The SDM offers ( just like the CHDK) the
Edge Overlay as an
aid:
f First, switch on the Edge Overlay by clicking the ALT button and then
pressing the FUNC/SET button for a second. You should now see a no-
tice such as “Allocated xxxxxx bytes”. Press ALT again to leave the <Alt>
mode.
f
Press the shutter button a first time. The Edge Overlay should appear
now in the form of bright yellow lines. Also, the message “frozen” is
shown.
f
Move the camera a bit to the right, but not too much. Use the distance
between your eyes as a guide and also see below. For macro work you
can choose a much smaller distance, and for landscape work you can
exaggerate the 3D impression by choosing a larger distance.
f Now register the camera so that the edges of the nearest subjects
match. The difference between the edges of the farthest objects
( devia-
tion) should not exceed two millimeters on the screen (assuming a
display width of approximately two inches).
f
Take the second shot.
f
Now switch to Replay mode . Navigate to the first (left) image and half-
press the shutter button
3
to select it. Then navigate to the second (right)
image and half-press the shutter button again. The display should now
show a red/cyan overlay of both images
( anaglyph) . If you have your
red/cyan goggles with you, you can view the image in 3D right away.
Under
ALT > MENU > Stereo > Playback mode you can choose between a
monochrome anaglyph, a color anaglyph, or a side-by-side pair.
The main purpose of this display option is, however, to check the
registration of both images. If you want to magnify the anaglyph, you
must first zoom in on the left image, half-press the shutter button, then
3 On the S2 IS, S3 IS, S5 IS, and A550, use FUNC/SET instead of the shutter
button half-press.