1. An electronic imaging device, comprising: an optical objective for collecting optical radiation from an object, the objective having an optical axis; an image sensor, comprising a matrix of optical detectors arranged in a plane that is substantially non-perpendicular to the optical axis, the image sensor having a lateral dimension in the plane; and a turning mirror, having an optical surface that is positioned so as to reflect the radiation collected by the objective in order to form a focused image in the plane of the image sensor, while a maximum distance from the optical surface to the plane of the image sensor is substantially less than the lateral dimension of the image sensor.