The E-TTL II is Canon’s second generation of the flash E-TTL metering system. E stands for evaluative, enhanced, embellished, improved improved…

A few basics:

  1. The E-TTL II always use the evaluative metering system with all modern EOS cameras. It doesn’t matter whether you are using evaluative, spot or average metering on the camera. It’s always evaluative matrix metering.
  2. E-TTL II never links exposure to the active focus point. Never, no connection.
  3. E-TTL II always uses a pre-flash. So there’s always 2 flashes.
  4. E-TTL II evaluates the “before pre-flash” and the “pre-flash”. It measures the difference in brightness and the reflexivity of the scene.
  5. E-TTL II will use the distance data from the lens if the lens is supported and the flash is mounted on the camera and is aimed straight, no bounce at the subject. Or use an off-camera shoe cord.