The white man's album

In and Out of Focus is a deceptively slim, beautifully illustrated book, written by Christaud Geary, curator of the Eliot Elisofon photographic archives at the Smithsonian's National Museum of African Art in Washington DC.

Accompanied by an essay by Krysztof Puskova, this book is almost certainly the first major publication "to examine how widely disseminated images by Euro-American photographers created and perpetuated ideas and sentiments about the peoples of central Africa who lived under colonial rule". It also explores the role Africans played in projecting and creating images of themselves for foreign photographers and how they adopted photographic technology and made it their own.

Images of central Africa were made as early as 1483 when Portuguese navigators reached the mouth of the river Congo - travellers' accounts are illustrated in books and maps in engravings. Then, in the 16th and 17th centuries, during a period that heralded the gruesome transatlantic slave trade, images in the "noble savage tradition" portrayed Africans in classic poses, often reminiscent of antiquity. Westerners therefore came to see Africans as the very opposite of Europeans - unspoilt children of nature.

When, in the late 18th century, Europeans recognised the inhumanity of slavery, the powerful antislavery movement began and western perceptions of Africans changed dramatically towards protecting them. In the ensuing age of exploration, Europeans concentrated on penetrating Africa's interior; explorers such as Livingstone described the "dark continent" as a primordial wilderness inhabited by primitive people. Thus, negative racist connotations were born. Other juxtapositions expressed in visual form were the "naked" and "clothed" categories and the "light" and "dark" metaphor, which implied the superiority of the light ("pure") westerners. When exploration gave way to colonisation, the scramble for Africa pitted European nations against each other and, in particular, Leopold I... of Belgium secured for himself enormous parts of central Africa with the help of Henry Morton Stanley.

Illustrations in magazines and travel books, as well as photographic images in stereographs and postcards, were crucial to popularising the imperial enterprise and were at the heart of propaganda of the colonial period that ended with the independence of African nations in 1957-61.

Photographs could be reproduced as half-tones as early as 1885; many of these form the bulk of the material reproduced in this superlatively researched book. There is an excellent chapter that painfully includes details of the Congo Free State and its imagery and photographs seen from a present-day perspective, as well as details of imagery from the anti-Leopold campaign. Curiously, the power of imagery - the medium that had helped to build the modern and progressive Congo Free State - helped to destroy Leopold's regime.

There are two extraordinary chapters on the work of Casimir Zagourski (1883-1944). In the years between the two world wars no photographer visually articulated popular ideas about the peoples of central Africa more eloquently than he did. His exquisitely executed black-and-white prints, many of which are reproduced in this volume, have instilled ideas about a traditional African world coveted by westerners.

The final chapter is on Africans and photography. Peoples in central Africa witnessed the advent of photography at different times and in different ways. Initially, image-makers subjected Africans to the dehumanising process of undressing and remaining still in prescribed poses, but with Africans' growing understanding of the photographic process, the people used the act of being photographed for their own purposes and played an increasingly active part in it. Central African rulers presented themselves to the camera in the way they wanted to be seen. Since their first encounter with westerners, many of the early and frequently photographed people (such as the Mangbeth of the northeastern Congo, the Tutsi in Rwanda, and the Kuba in the south-central part of the Congo) have become icons in the central African image world.

In the foreword, David Binkley, deputy director and chief curator of the National Museum of African Art, voices the hope that this and similar publications will spawn continued interest and support for a unique international resource. For almost 150 years photography has been a force in influencing how we have looked at, and thought about, the African continent and its peoples. This publication - which is only a small part of the over 280,000 images in the National Museum of African Art - will give the 21st-century viewer a flavour of the compelling and exceptionally beautiful images that represent an extraordinary period in African history.

Christopher Ondaatje is on the council of the Royal Geographical Society. His most recent book on Africa is Hemingway in Africa: The Last Safari .