through the lens (photo camera) (TTL)

Through The Lens (TTL) is a camera technology term. With this technology, exposure metering and focusing are performed through the lens.

The camera settings can be made via the electronic viewfinder, in whose display the various exposure values and other settings are shown.

The Through The Lens method is used with compact cameras and SLR cameras. In the latter, the settings are made via an oscillating mirror that flips up when the shot is taken, exposing the light channel to the image sensor.