Canon EOS 55 Service Manual page 64

Part 2: Technical Information
3) Camera and Speedlite Operation Steps
This shows the E-TIL Exposure System operation steps executed by the EOS
50/55/Elan II and Speedlite 380 EX.
Camera operation Speedlite 380 EX Operation
ISO film speed
AV 32
Lens AVo
22
16
11
6
5.6
•
2.9
2
1.4
1.0
I
I
(1) Lens f/No.
.I
(1) Zoom Auto
I
I
I
1
(2) Flash-ready Signal
I
AF
(2)Ambient light metered
---------------t
Briahtness Information
(3)Algorithm calculation
/
/
I/
/
/
/
1 1
(4) Sync Speed
I
(5) Flash Aperture
TVauto 60-4000
I
AVauto 2.8-22
I
I
(6) Real-time metering for
framing change detection
~
,---------------.1.
(7) Ambient light metering before preflash
I
(3) Preflash
I
(8) Preflash Metering :
I
1(9) High reflectivity correction
I
1(10) Framing change detection
I
1(11) Main flash output calculation
Flash oulout information sent
l
(4) Main Flash
(12) Exposure control
I
(seconds)
TVauto
~
X speed: Normal Flash
Control completed
I
l
(13) Exposure Completed
Fig. 2-17 E-TTL Autoflash Operation
2-20
TVauto > X speed: FP flash