One of the starting points for this publication of the Magnum photo-collective's impressive collection of contact sheets and the accompanying exhibition is that this once intrinsic part of photographic work has now been "rendered obsolete by digital photography". However, the book shows examples of contact sheets produced as recently as 2010.
The contact sheet is associated with shooting on film to produce negatives, which are then printed as positives through direct "contact" with photographic paper.
The images are printed at the size of the negative and can be seen, edited or selected for larger prints. While this form of production is no longer practical for fast-paced photojournalism or much everyday photography, many photographers do still use film for various reasons.
As the contact sheet usually shows the full sequence of images as they were shot, they can be looked on as evidence of the photographer's method and of elusive notions of photographic truth. They can trace how the "final" shot was arrived at - was it a "decisive moment" or a contrived set-up?
With images shown in sequence, this collection acts like a history book of the important moments of the 20th century as photographers have recorded it. In seeing the contact sheets we see more of those moments unravelling.
There are hundreds of fascinating images collected here. Of particular interest is Bruce Davidson's coverage of the US Civil Rights movement in the 1960s. Davidson wanted to document the everyday experiences of African Americans as well as marches and conflict.
One contact sheet shows on the same roll of film a series of portraits of a woman at home, followed by the gruesome scene of the murder of a civil rights activist by the Ku Klux Klan.
Bruno Barbey's images of the 1968 Paris riots were later made into a short film, while Stuart Franklin captured the crushing of the protests in China'sTiananmen Square in 1989 (see above).
Gilles Peress photographed Bloody Sunday in 1972. The contact sheets show how the day progressed from a peaceful march to a massacre by the British army and were used as evidence at the recent Saville inquiry.
The book is very expensive so I recommend visiting the exhibition.
Magnum Contact Sheets is showing at the Magnum Print Room, London, until 27 January 2012