Professional Digital Cameras: This paper is concerned solely with cameras which use area solid state imagers and that are capable of producing colour images with six million pixels and more. Also, only cameras with a permanent link to a host computer, i.e. in a more or less stationary environment are considered, such that there are no severe limitations with respect to storage capacity and power consumption. This implies that the primary design goal can be image quality. The basic characteristics of the sensors most commonly used in such cameras are described, together with methods to improve their performance in terms of resolution, field of view, alias suppression and live imaging speed.