An attachment which may be fitted to a standard crystallographic goniometer head for the purpose of taking x‐ray section topographs is described and its application in synchrotron x‐ray topography is illustrated. A collar attached below the arcs and translation slides of the goniometer head provides a bearing for a rotatable sleeve, concentric with the goniometer axis. The sleeve carries a removable x‐ray entrance slit and a removable mirror used for angular setting by optical means. The device is easily transferable between topograph cameras at conventional x‐ray sources and synchrotron radiation sources. It can be rapidly aligned at either source.