  The algorithms used for reduction of data obtained in a Fabry-Perot
interferometer mode of the new focal reducer of the 6m telescope SCORPIO are
described. The main attention is focused on the procedures of photometry
correction of channels and night sky emission subtraction, which is especially
important for observations with a CCD in comparison with a photon counter. The
influence of various sources of errors on measurements of radial velocities in
a data cube is investigated. Examples of velocity field construction by using
emission lines in the galaxy NGC 6951 and absorption lines in the globular
cluster M 71 are presented.
