Exposure Calculator made by the Regional Soviet Prodkombinat of Dzerzhinsky .

This type of guide was used by photographers before selenium light meters became widely available. It measures just 9.5 x 11 x 1 cm. and dates from the late 1920s or 1930s. The impressed, gold-printed cardboard cover has a "PDR" logo and reads "GUMP LENGORISPOLKOMA PROMKOMBINAT DZERZHINSKY RAISOVET" (loosely: "Main Controller Agency of Metal Industry of Leningrad Executive Committee - Industrial Combine of Dzerzhinsky Regional Advisory").

The back is impressed with Cyrillic writing relating to the original price of the booklet. Inside, in a pocket, resides a round adjustable exposure calculating device whose wheels are actual photographs, contact printed onto silver-gelatin emulsion coated photographic paper. There may have also been a paper table in the opposite inside pocket, now missing. The booklet is hand-made and although very popular and numerous at the time they were used, few have survived, having been discarded after the widespread use of selenium and electronic mechanical light meters.