Olympus CAMEDIA C-5000 Zoom Reference Manual page 178

Glossary of terms
TTL (Through-The taking-Lens) System
To help adjust exposure, a light receptor built into the camera directly
measures the light passing through the lens.
TTL-AUTO
For use with an external flash. Light emitted by the flash is measured by the
light receptor in the camera as it passes through the lens. A signal is then sent
to adjust the external flash intensity.
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