How does TTL Flash Metering Work?
TTL Metering was invented in the late 70’s by Nikon to improve on the current flash system which used a sensor in the flash to determine proper output. The much improved Through The Lens metering system allowed for more accurate metering and started Nikon’s prevalence in the 35mm strobe market.
There are some times where the flash can be fooled. Check out the video for samples as well as when I primarily use TTL Auto Flash.