[en] The vector and pseudoscalar decay constants are calculated in the framework of the Field Correlator Method. Di-electron widths: Γ_ee(J/ψ) = 5.41 keV, Γ_ee(ψ'(3686)) = 2.47 keV, Γ_ee(ψ''(3770)) = 0.248 keV, in good agreement with experiment, are obtained with the same coupling, α_s = 0.165, in the QCD radiative corrections. We show that the larger α_s = 0.191 ± 0.004 is needed to reach agreement with experiment for Γ_γγ(χ_c) = 7.22 keV, Γ_γγ(χ_c(³P0)) = 3.3 keV, Γ_γγχ_c(³P₂)) = 0.54 keV, and also for Γ(J/ψ ^→ 3g) = 59.5 keV, Γ(J/ψ ^→ γ2g) = 5.7 keV. Meanwhile, even larger α_s = 0.238 gives rise to good description of Γ(ψ' ^→ 3g) = 52.7 keV, Γ(ψ' ^→ γ2g) = 3.5 keV, and provides correct ratio of the branching fractions: (Β (J/ψ → light hadrons)/Β (ψ' → light hadrons) = 0.24.