Still, there are archival photographs of Aeroscope cameras being pumped by British combat cameramen as late as in 1940, at the beginning of World War II.

As soon as Poland regained its independence in November 1918, Prószyński returned with his English wife, Dorothy, and children Kazimierz junior and Irena.

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, which Prószyński intended to mass-produce for schools and the public.

Kazimierz Prószyński died in the Nazi concentration camp of Mauthausen in spring of 1945, as the prisoner number 129957, shortly before liberation.

Kazimierz Prószyński is regarded along with Bolesław Matuszewski and Jan Szczepanik as one of the most important pioneers of Polish cinema and cinematography.