Preliminary results of new high-resolution and S/N ratio spectra of central stars of planetary nebulae (CSPN) are presented. The atmospheric parameters (Teff, log g, helium abundance) are derived using NLTE techniques. The results obtained confirm the conclusions of Mendez et al. (1988): (1) the distance scale of CSPN is greater than usually assumed; (2) as a consequence the luminosities of the CSPN agree with the predictions of evolutionary tracks, and (3) for a given temperature, the CSPN with strong winds are more massive than the others.