Attended King's College, Auckland 1911 - 1919 followed by a year at Christ's College, Christchurch. Attended night classes at Elam School of Art. In 1933, married Joyce Patricia Fitzherbert. In 1940, married Melva Martin. Established a commercial photography studio in Auckland - at various Auckland addresses - until settling at 110 Queen Street in 1938 where it remained until Firth's retirement in 1974. Established a second photographic studio in Cathedral Square, Christchurch, in mid-1940s, run by Natalie Swann. Auckland City Libraries hold a collection of over 100,000 Firth negatives.