The invention relates to an illumination device for producing an illumination pattern (6) with a variable shape and luminous intensity to a target (5). The illumination device comprises at least partly translucent and light-reflecting optical piece (1), several light sources (3) producing a conical light pattern, fixed in such a manner that the position and angle of the same can be adjusted in relation to each other and/or to the optical piece (1), and an electronic control unit (4) that is electrically coupled to each light source (3) in such a manner that the intensity of the light produced by each light source (3) can be adjusted under the control of the control unit (4). The optical piece (1) is attached in such a manner that the light beams produced by the light sources (3) are arranged to propagate at least partly via the optical piece (1) to the target (5) to be illuminated. The light beams produced by each light source (3) are arranged to form a part of the illumination pattern (6) produced by means of the illumination device, the form of said illumination pattern being substantially independent of the external form of the optical piece. The invention also relates to a method for producing an illumination pattern (6) with a variable shape and luminous intensity to a target. In the method, conical light patterns are produced by means of several light sources (3), of which light patterns at least some are directed via the optical piece (1) to the target (5) to be illuminated. The shape of the illumination pattern (6) produced by means of the method is substantially independent of the external shape of the optical piece.