There is provided an electron microscope capable of recording images in a shorter time. The electron microscope (100) includes: an illumination system (4) for illuminating a sample (S) with an electron beam; an imaging system (6) for focusing electrons transmitted through the sample (S); an electron deflector (24) for deflecting the electrons transmitted through the sample (S); an imager (28) having a photosensitive surface (29) for detecting the electrons transmitted through the sample (S), the imager (28) being operative to record focused images formed by the electrons transmitted through the sample (S); and a controller (30) for controlling the electron deflector (24) such that an active electron incident region (2) of the photosensitive surface (29) currently hit by the beam is varied in response to variations in illumination conditions of the illumination system (4).