The optical properties of carbon nanofilms in the sp (linear-chain carbon, LCC), sp2 (amorphous carbon) and sp3 (diamond-like carbon) hybridized state have been studied. The films were synthesized by the ion-plasma method and subjected to heat treatment (annealing) at various temperatures in air. Optical properties were measured by spectrophotometry and Raman scattering. Methods are proposed for determining the phase composition of carbon films of various sp hybridization states based on measurements of transmission spectra in the visible region of the spectrum.