eTTL - what is it?

eTTL ("Evaluative Through-the-Lens Mode") is a flash control developed by Canon for the optimal illumination of a subject. In this practical tip, we explain exactly what this is all about.

How does eTTL work?

With the eTTL method, the measurement takes place through your current lens (Through The Lense). This has the advantage that the flash control is tailored to your lens:

• A short measuring flash is generated just before the actual image.
• The camera uses this to calculate the perfect light intensity.
• To do this, the camera only needs a sensor.

The difference between TTL and eTTL

TTL ("Through-the-Lens Mode") is the predecessor of eTTL and calculates the strength of the flash during the shot:

• The flash initially fires at full strength.
• As soon as the camera detects that the subject is sufficiently illuminated, it sends a stop signal to the flash.
• In contrast to the eTTL method, your camera requires two measuring cells (sensors).

Conclusion

eTTL and TTL are the perfect instrument for you if you want to take good pictures quickly. More creative images with, for example, plays of light and shadow still require manual control.

Note: For eTTL flashing, you need Canon cameras and the corresponding flash units. Learn how to transfer images with EOS Utilities here.