This globally renowned photographer has been taking photos since he was ten years old. At the age of sixteen, he won a gold medal at a national photography exhibition, and his first works were published in the Swiss magazine Camera. After completing his university studies, he worked as a professional photographer for the weeklies Svět v obrazech and Domov a svet. He was also a fashion photographer in Bratislava and Prague, and later for a long time in Berlin and Paris. In addition, he cooperated with prestigious foreign magazines such as GEO, Stern, Merian, and Paris Match.

As a member of the German Bielderberg society, he brought "news in photos" from Africa, Indonesia, Thailand, Australia, the USA and Russia. His images of old Bratislava, its streets, summer days on the Danube embankment, and the iconic photo of nuns with their backs turned looking at the city were extremely popular, and his book Bratislava moja (My Bratislava) is comprised of photos featuring Kállay’s unique perspective. Furthermore, he demonstrated his love for Prague in Franz Kafka a Praha (Franz Kafka and Prague).

Kállay tried to capture something new, in places where others had not been, and when searching for a subject he remembered the advice of photographer Karol Hájek: “Try to look at things from a different perspective than everyone else.” Last but not least, he remembers meeting an old woman on the Trans-Siberian Railway. She asked him where he was from, what his nationality was, and whether he believed in God. He answered her, but it didn’t seem as if she was listening. After a pause she said, “But it doesn’t matter who you are, the important thing is that there is no war.” It was a conversation that he would never forget, and was probably more important to him than the photo he took to remember her face. His photographs have been exhibited in prestigious galleries all over the world.