His studio was based at Vestergade 21[2] and he became a board member of the Funen Photographers' Association.

[1] Folkmann returned to Copenhagen in 1910, He also worked as a cinematographer on a few films directed by Vilhelm Glückstadt in 1911-13 and took over Frederik Riise's former photographic studio at Amagertorv 33 in 1914.

He played a central role in the foundation of association's school of photography in 1016 and served as its first leader from in 1916 tp 1021 and again from 1934 to 1944.

[1] Folkmann married the Scanian Hilda Andersson (16 August 1862 - 12 December 1928), a daughter of the farmer Anders Anderson and Sophia Sjönström on 26 September 1890 in St. John's Church in Nørrebro.

He was after her early death in 1928 married to her half sister Anna Matilda Anderberg (born 6 February 1894) on 23 November 1936 in Søllerød Church.