Complex sentence: In 1937 the Arri Group introduced the world's first reflex mirror shutter in the Arriflex-35 camera, an invention of their longtime engineer Erich Kaestner.
Split into simpler sentences: In 1937 the ARRI Group introduced the world's first reflex mirror shutter in the ARRIFLEX-35 camera. An invention of their longtime engineer Erich Kaestner.