320 blue stars of the Giclas and Luyten catalogues with positions δ 15° and magnitudes have been observed photometrically in UBVRI and Stromgren colours with the ESO lm telescope at La Silla in order to increase the number of close-by white dwarfs. From their Strömgren colours more than 120 stars belong to the white dwarf region. But, as outlined by Rupprecht and Bues (1983), a combination of the photometric systems and the combined two-colour diagrams (R−I)/(U−V) and (R−I) / (u−b) provide additional information on binary components. Fig.1 shows a sample in the (R−I)/(u−b)diagram. For (u−b) <.2 and (R−I) <.2 a second component is present.