  Hadronic final states with a hard isolated photon are studied using data
taken at centre-of-mass energies around $\Mz$ with the OPAL detector at LEP.
The strong coupling $\as$ is extracted by fitting event shape variables for the
reduced centre-of-mass energies ranging from 20 GeV to 80 GeV, and the energy
dependence of $\as$ is studied. Combining all the values using different event
shape variables and energies gives:
  \asmz=0.1176\pm 0.0012(stat.)^{+0.0093}_{-0.0085}(syst.).
