1. A method of performing tomographic imaging of a sample in a charged-particle microscope, comprising the following steps: providing a beam of charged particles that propagate along a particle-optical axis; providing the sample on a sample holder that can be tilted relative to said beam; in an imaging step, directing the beam through the sample so as to form and capture an image of the sample at an image detector; repeating this procedure at each of a series of sample tilts so as to acquire a corresponding set of images; in a reconstruction step, mathematically processing images from said set so as to construct a composite image of the sample, wherein: in said imaging step, for a given sample tilt, a sequence of component images is captured at a corresponding sequence of focus settings; in said reconstruction step, for at least one member of said series of sample tilts, multiple members of said sequence of component images are used in said mathematical image processing.