flash exposure circuitry present in nearly all film-based EOS camera bodies, the EF-M being the
only notable exception. When attached to an E-TTL capable film-based EOS camera body, the
Speedlite 200E will function, but only as a TTL flash, without any E-TTL features such as high-
speed sync and Flash Exposure Lock.
Note: The TTL automatic flash exposure function does not work with E-TTL-only EOS camera
bodies, such as the EOS D30 and later digital cameras.
The TTL circuit is activated whenever the flash is switched out of Manual mode. During flash
exposure, light is metered directly from the film plane when the shutter is open. During the flash
burst, as soon as adequate flash exposure is detected, a "TTL" signal is sent via the hotshoe to
quench the Speedlite.
To make use of TTL flash, first set the camera to Av, Tv, or M mode. Push the "MODE" button on
the Speedlite until the LCD panel shows "ATTL" or "TTL". Make sure the READY light is
glowing on the flash, and that the FLASH indicator in the camera viewfinder LCD is lit. To take a
picture, fully depress the shutter button on the camera.
Exposure Compensation
Flash metering assumes an average reflectance for the scene. In cases where the scene is unusually
reflective or unusually dark, the flash exposure can be adjusted to suit the scene. Flash Exposure
Compensation (FEC) can be applied in increments of one third of one stop within a range of 3
stops.
To make the flash exposure brighter, push the "+" button on the Speedlite control panel until the
desired compensation is reached (range 0 to +3.0).
To make the flash exposure darker, push the "-" button on the Speedlite control panel until the
desired compensation is reached (range 0 to -3.0).
A-TTL
Preflash
A-TTL (Advanced TTL) was Canon's extension of the TTL flash metering system. The primary
feature of A-TTL was the addition of a infrared-filtered second flash tube and a forward pointing
flash exposure sensor on the front of the Speedlite. As soon as the shutter button was half-pressed,
an invisible preflash was emitted and the reflected signal from the subject measured to determine
the subject reflectance, and indirectly, the subject distance. A strong reflectance signal indicated a
close-by subject, allowing the use of a narrow lens aperture, while a weak reflectance signal results
in the automatic selection of a wider aperture. In the case of indirect or bounce flash, the infrared
preflash would not be accurate, so a visible light preflash from the main flash tube was employed.
To make use of A-TTL mode, first set the camera to "FULL AUTO" (Green) mode or to "P" mode.
Push the "MODE" button on the Speedlite until the LCD panel shows "ATTL". Make sure the
READY light is glowing on the flash, and that the FLASH indicator in the camera viewfinder LCD
is lit. To take a picture, fully depress the shutter button on the camera.
Note: The A-TTL automatic flash exposure function does not work with E-TTL-only EOS camera
bodies, such as the EOS D30 and later digital cameras.
Out-of-range
A very weak A-TTL reflectance reading would indicate that the subject is too far away for adequate
Darkest
Darker
Neutral
Brighter
Brightest
-3
-2
2
/3 -2
1
/3 -2
-1
2
/3 -1
1
/3 -1
-
2
/3 -
1
/3 0 +
1
/3 +
2
/3 +1
+1
1
/3 +1
2
/3 +2
+2
1
/3 +2
2
/3 +3
Pagina 6 di 8
EOS Documentation - 430EZ