Synchrotron radiation diffraction imaging (‘topography’) was used at the ESRF to visualize ultrasonic standing waves in a magnetoacoustically excited FeBO3 crystal. Images were recorded at long sample-to-film distances (up to 1.5 m) without substantial loss of resolution. The resonant patterns reveal that the crystal acts as a pulsed X-ray focusing lens and strongly depend on both the amplitude of the magnetic field and the sample-to-detector distance. Different resonant frequencies can also lead to more complicated images due to interference effects of several vibrating modes present in the crystal. A model is proposed followed by a numerical integration which predicts the focusing of the X-ray beam and demonstrates the agreement between theory and experiment. This effect could be used to simultaneously monochromatize and focus the X-ray beam.