The present invention relates to an apparatus (10) for imaging an object. It is described to position (210) an X-ray detector relative to at least one X-ray source such that at least a part of a region between the at least one X-ray source and the X-ray detector is an examination region for accommodating an object. In a first mode of operation, with the at least one X-ray source a first focal spot is produced (220), such that at least some first X-rays produced at the first focal spot pass through a first grating of an interferometer arrangement, the first grating positioned at a first position, and such that the at least some first X-rays pass through a second grating of the interferometer arrangement, the second grating positioned at a second position. In the first mode of operation, the at least some first X-rays are detected (230) with the X-ray detector at a detector position. In a second mode of operation, with the at least one X-ray source a second focal spot is produced (240), such that at least some second X-rays produced at the second focal spot avoid the first grating at the first position. In the second mode of operation, the at least some second X-rays are detected (250) with the X-ray detector at the detector position.