Photography: Magnum Contact Sheets, ed Kristen Lubben

The contact sheet, which offers that thrilling first look at the contents of a roll of film, has been compared to the artist's sketchbook.

In this collection of more than 100 of them from the archives of the famed Magnum agency, the US photojournalist Leonard Freed describes them as "private" and belonging to him. This book offers an intimate glimpse into its contributors' working processes, then, and at the behind-the-scenes construction of now famous pictures.

It is also, Martin Parr notes, an evocative epitaph to something made obsolete in the digital era. Shown above, Margaret Thatcher at the 1981 Conservative Party Conference, by Peter Marlow.