  We consider the problem of uniqueness of static and asymptotically flat
Einstein-Maxwell spacetimes with a photon sphere $P^3$. We are using a
naturally modified definition of a photon sphere for electrically charged
spacetimes with the additional property that the one-form $\iota_{\xi}F$ is
normal to the photon sphere. For simplicity we are restricting ourselves to the
case of zero magnetic charge and assume that the lapse function regularly
foliates the spacetime outside the photon sphere. With this information we
prove that $P^3$ has constant mean curvature and constant scalar curvature. We
also derive a few equations which we later use to prove the main uniqueness
theorem, i. e. the static asymptotically flat Einstein-Maxwell spacetimes with
a non-extremal photon sphere are isometric to the Reissner-Nordstr\"om one with
mass $M$ and electric charge $Q$ subject to $\frac{Q^2}{M^2}\le \frac{9}{8}$.
