Synchronized Flash - Canon Camera Hackers Manual

By repeatedly pressing
f
until you reach a screen entitled " TWIN CAMS".
Zoom to the telephoto position (mandatory!). Focus on the nearest
f
object and half-press the shutter button. The entry "Near" in the OSD
screen will be updated. It will turn red if the subject distance is too near
(section 7.7.1).
Now focus on the farthest object and half-press the shutter button. The
f
entry "Far" will be updated.
Now zoom back to the desired zoom position. The calculated deviation
f
(in mm) is displayed in the entry Deviation. This value is the maximum
deviation required for the current scene (based on the captured dis-
tances). It should be lower than dmax. A horizontal bar graph shows the
Deviation value as a percentage of dmax. If the bar graph is red, the
Deviation value is too big (more than 100% of dmax). In that case, you
should consider zooming out more or moving farther away from the
subject.
Now you are ready to display the guidelines. First, disable the option
f
ALT > MENU > Stereo
on both cameras, go to
ters > Grid settings. Enable the option Show grid lines and invoke the
function Load grid from file... to load Deviation_H.GRD (DEVIAT~1.GRD
on DryOS), align the centerline of the left camera with a significant
point on the nearest object. Do the same with the centerline (the left of
the two lines shown) of the right camera. Next, align the centerline of
the left camera with a significant point on the farthest object and do
the same with the right line (deviation indicator) of the right camera.
The left camera does not show a deviation indicator.

7.7.5 Synchronized flash

When working with a twin camera set-up, it is also possible to use the
built-in flash units of both cameras. To enforce identical exposure settings
on both cameras, it is necessary that both cameras do fire the flash. All you
have to do is:
Set up both cameras as twin cameras as usual. Also enable the option
f
ALT > MENU > Stereo
If you use Overrides (section 4.3.1), use the same Tv values ( shutter
f
speeds) for both cameras. If the cameras are set to automatic exposure,
the cameras will set the exposure time to 1/60 sec.
Turn the flash on (AUTO or ON) on both cameras. If your cameras
f
support second-curtain mode for flash, be sure to set the flash to first-
curtain mode.
ALT > LEFT or ALT > RIGHT,
> Disable deviation guideline on both cameras. Also
ALT > MENU > Advanced Menu
> Synchronization > Add User and flash delays.
browse the SDM OSD
> OSD parame-
7.7 Stereo photography
Figure 7-12
The Twin Cams OSD. Below the
Deviation entry is the bar graph that is
within limits. If it were not within
limits, the bar would be red and you
would need to zoom out, increase the
distance to the subject, or reduce the
spacing between the cameras.
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