A small dental X-ray apparatus has an X-ray emitter 3 fixed to a cantilever 2, which X-ray emitter 3 can be manually adjusted in space relatively to a basic position by means of the cantilever 2. Means 14, 16, 18 are provided for the acquisition of the position and alignment of said X-ray emitter (3) in space.The method serves to automatically detect deviation of an actual position in space from a target position in space, which deviation is indicated by signalling elements 25 and the operator is informed on the quality of the actual position and on the direction of a change in the actual position which may be required to acquire an improved position.