Kazimierz Prószyński was a Polish inventor active in the field of cinema. He invented the widely used hand-held Aeroscope camera. In 1894, Kazimierz Prószyński built one of the first movie cameras. In 1922, he managed to establish a company Oko (Polish for: eye) to promote a simple amateur camera of his construction with the same name but the economic crisis in the 20s stopped the plan. In WW2 the Germans uncovered his workshop and suspected him of conspiracy. He was arrested on August 25, 1944, during the Warsaw uprising. He died in Mauthausen-Gusen concentration camp in spring of 1945, as prisoner number 129957, shortly before liberation.