Canon SPEEDLITE 540EZ Service Manual page 28

Part 2: Technical Information
1.6 Manual Multiple (Stroboscopic) Firing
1) Setting the firing conditions
Whereas the 430EZ is equipped with a stroboscopic firing function providing a
selectable multi-firing frequency range of just 1~10 Hz, the 540EZ expands the
frequency range to 1~100 Hz. Moreover, the number of firings can be set to "- -"
(hyphen display: unlimited number of firings) or from 1 to 100 times.
2) Shutter speed and aperture settings
(1) Shutter speed
When using the 540EZ's multiple flash function, slow shutter speeds are
naturally used to achieve the stroboscopic effect. There are two ways to set the
shutter speed, as follows:
1. Bulb
The multiple firings start simultaneously with the start of exposure at SW-2
ON. Then when the firings are completed, the user releases the shutter
button to stop the exposure.
2. Setting an appropriate shutter speed
The appropriate shutter speed is any shutter speed longer than the multiple
firing time calculated by dividing the set number of firings by the firing
frequency.
* Example for when no. of firings = 20 and firing frequency = 10 Hz:
20 + 10 = 2 sec.
— The user should set a slow shutter speed of 2 seconds or longer.
(2) Aperture
The aperture is set in the same way as during normal manual firing, based on
the shooting distance and flash output level.
1.7 Downward Tilt Head
In addition to the upward and left/right bounce capabilities of previous flash
units, the 540EZ also provides the capability to tilt the flash head downward at an
angle of 7°.
With the head at the standard O° position, the flash coverage is sufficient for close
distances down to 1~1.5 m (the minimum distance differs depending on the lens
and zoom setting used), but when taking pictures at even closer distances, the
flash illumination falls off at the bottom edge of the picture. For such close-
distance shooting situations, even illumination can be obtained by tilting the flash
head 7° downward and zooming the flash to the 24mm zoom position or attaching
the 18mm wide panel. As a rule, this configuration is appropriate for shooting
distances of 0.5~2 m. At distances closer than 0.5 m, since subjects cannot be
completely covered by the 540EZ while it is attached to the camera's accessory
shoe, we recommend using the Off Camera Shoe Cord E to separate the flash from
the camera to properly light the subject.
*Figure 28 on the following page shows the difference in coverage between the
standard 0° position and the 7° downward tiling position.
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