Siewert's photographs have appeared in the Sydney Morning Herald and the book, "The Last Anzacs: Lest We Forget" with the author Tony Stephens. He has photographed many celebrities, including the Dalai Lama, Christina Aguilera, and Nicole Kidman and he won a Walkley award for his photojournalism in 2007. In 2001, Siewert was also awarded a fellowship to work in Bangkok, Thailand for Asian newspaper, The Nation. Siewert's photography has been included in solo and group exhibitions at the Leica gallery in Solms, Germany, the Museum of Sydney, the Centre for Contemporary Photography in Melbourne, the State Library of NSW and Albury Regional Art Gallery.
- The Last Anzacs: Lest We Forget, Tony Stephens (Author) and Siewert, Fremantle Arts Centre Press (April 2003) ISBN 978-1-920731-36-6
- Centre for Contemporary Photography, Melbourne Australia, 2005
- Rockabilly: living the 50s, Museum of Sydney, 2008