It is well known that increased surface roughness of SF6 insulated electrode arrangements is significantly lowering the breakdown voltage , . This effect becomes stronger with rising pressure and homogeneity of the electrodes. Since each breakdown changes the surface condition of the electrodes, it becomes very ambitious to measure breakdown probabilities in a statistical meaningful way. To cope with this difficulty a surface tracking device was introduced, consisting of a photo camera and image processing software. This device aids to decrease statistical dependencies through post processing of the measured data after an experiment.