Photoelectric UBV photometry of stars was carried out in the angular vicinity (radius = 15′) of 3 planetary nebulae. An extinction distance relation was constructed for the line of sight towards each planetary nebula. This relation was verified by published data on nearby stars and star clusters. The distances derived are 850 ± 300 pc for PK 128 −04 1 (S 188, Simeis 22), 400 ± 200 pc for PK 149 −09 1 (HW 4), and (less reliable) 800 pc ± 400 pc for PK 224 +01 1 (We 1–6). For the central star of PK 224 +01 1 our observations gave V = 15.76 ± 0.03 mag, (B–V) = −0.08 ± 0.03 mag and (U–B) = −0.87 ± 0.03 mag.