This article addresses the reconstruction wavelengths and half-power widths of DCG holograms of various gelatins. Of the gelatins studied (four inert, two active, and one PA), the reconstruction wavelength and half-power width of the PA gelatin greatly deviated from those of the other six. The reconstruction wavelengths and half-power widths of the DCG holograms of the two active gelatins had no significant differences from the four inert gelatins, although the diffraction efficiencies of the active were much higher than the inert gelatins. In addition, the DCG holograms of the PA gelatin had more secondary diffraction peaks than those of the active and inert gelatins. The article also discusses the causes of these differences from the microstructure of various gelatins.