He worked for Leitz and invented the Leica camera which came to market in 1924. Up until that time cameras were big and heavy but his new small-format camera changed photography.
Each year Leica gives the Oskar Barnack Award to one of the top photographers in the world. The window to enter has just opened. You can find out everything you need to know right here.
There's also a Newcomer Award if you're under 25 years old.