Modern DSLR cameras use the Phase Detect autofocus method to determine the correct point at which to focus the lens. This method is fast and generally accurate, and operated by light travelling through the lens. When you half-press the shutter button on your DSLR while looking through the optical viewfinder, it’s Phase Detect autofocus that’s used.
Explanation: His first opera, Rinaldo premiered at the Queen's Threatre in 1711, the same theater in which Andrew Lloyd Webber's Phantom of the Opera first saw the light of day in 1986.