Canon EOS 50 E - Page 69

Part 2: Technical Information
While the FE lock button is on, the Main Dial can be used. Even if the aperture
setting is changed, the flash exposure value remains locked. Therefore, the flash
output is adjusted accordingly to obtain the correct flash exposure of the subject.
7) When the shutter button is pressed halfway, ambient light is metered by the cur-
rent metering mode.
8) Exposure control calculated by the algorithm.
* The flash aperture and sync speed are set as described previously.
9) When the shutter button is pressed completely, the exposure sequence takes
place and the photo is taken.
5) FP Flash (High-speed sync)
As described earlier, FP flash is enabled when the EOS 50/55/Elan II is set to a Creative
Zone mode and the 380 EX's FP flash switch is on. FP flash (high-speed sync) enables
the camera to synchronize with the flash at all shutter speeds. FP flash restricts the
flash output to a stipulated level. By having a fixed-output flash fire over a continuous
period of time, flash control is possible even at high shutter speeds when the shutter
curtains do not open completely. Table 2-9 shows how the shutter speed synchronizes.
The sync speed can be set automatically (in the P, Av, or DEP mode) or manually (in the
Tv or M mode).
Figure 2-19 shows how the flash fires in the FP flash mode and normal flash mode. In
either case, the main flash is calculated and locked according ton-times the output of
the preflash. Therefore, even if exposure compensation is set while the FE lock button
is on and the sync speed becomes equal to or slower than the X-sync speed, the flash
mode changes automatically.
High-speed sync(Shutter speed > X-sync speed)
Shutter
Fla_s_h _ __.n ... __ __,
Preflash
Main flash (FP flash)
Low-speed sync (Shutter speed <= X sync speed)
Shutter
iii □□□~
Fla____.sh n.___ __ _______.~._____ __ _
Preflash
Main flash (Normal)
Fig. 2-19 FP Flash Diagram
2-25