A nomenclature is given to distinguish between absolute, direct and indirect condensation nuclei counters. In the first part, a direct condensation nuclei counter (CNC) with photographic recording—the Kanter Photographic Condensation Nuclei Counter (KPCNC)—is described. The expansion chamber and the recording procedure are discussed in detail. Experiments and calibrations are described to determine the working conditions of the instrument. Instrumental details are given in an appendix. In the second part two direct instruments are compared resulting in a correction factor for both direct instruments.