Canon TTL control refers to the ability of Canon cameras to automatically manage the output of an external flash unit to achieve proper exposure. This feature is essential for photographers looking to achieve accurate and consistent lighting in their images. By utilizing Canon's TTL control, photographers can rely on the camera to make adjustments to the flash output based on the scene's lighting conditions. This results in more professional-looking images without the need for manual adjustments. Canon TTL control is a valuable tool for photographers looking to streamline their workflow and produce high-quality photographs with ease.