https://www.cnet.com/news/galaxy-s10-shows-that-triple-rear-camera-phones-are-going-mainstream/ > There are several benefits to having three cameras on the back. The primary reason is the ability to switch between different focal lengths quickly. It is similar to a three-lens turret on an old Bolex camera that allowed you to change lenses simply by rotating the turret. > Bolex film cameras could be fitted with a turret of lenses making it fast to change focal lengths.