Alexander Borisovich Kapustyansky, also known as Isaac Borisovich Kapustyansky, was born in 1906 and was a Jew by nationality. Kapustyansky's family lived in Tashkent and moved to Moscow in 1921. The family had two sons Isaac and Georgy (born 1908). Isaac was well acquainted with photography since childhood, as his father was also a photographer and most likely it was he who gave Isaac and Georgy photographic knowledge. His brother George Kapustyansky was also a frontline photojournalist.

Isaac went to the front as a military photo correspondent from the very beginning of the war. According to documents, Isaac Borisovich Kapustyansky, Intendant 3rd rank, was drafted by the Sverdlovsk District Military Commission, Moscow Region, Moscow City, Sverdlovsk District. Isaac Kapustiansky went through the whole war and photographed on many fronts. He came all the way to Berlin, where he photographed the capture of the Reichstag. During the war he worked as a war photographer for the newspaper "Krasnaya Zvezda", but all the pictures published in the newspaper were under the name Alexander Kapustyansky, although even the medals were given in the name of Isaac. For what reason the name was changed and whether it was with the authorization of the photographer is not reliably known. But considering his nationality and non-party affiliation in wartime, as well as the mass post-war dismissal of Jews from public positions under the pretext of fighting cosmopolitanism, the change of name gave Isaak the opportunity to continue to be a photographer.

Isaac Kapustyansky ended the war with the rank of Captain of the Intendant Service. He was awarded the Order of the Red Star, the medal "For the Defense of the Caucasus" and "For the Defense of Moscow".