  We report on a dispersion relation for the \gamma\gamma\to (\pi\pi)_I S-wave
in isospin I emphasizing the low energy region. The f_0(980) signal that
emerges in \gamma\gamma\to \pi\pi is also discussed. Our results could be used
to distinguish between different \pi\pi isoscalar S-wave parameterizations. We
also calculate the width of the \sigma resonance to \gamma\gamma and obtain the
value \Gamma(\sigma\to\gamma\gamma)=(1.68\pm 0.15) KeV. Finally, we elaborate
on the size of the f_0(980) coupling to \pi\pi and show that its smallness
compared to the K\bar{K} one is not related to the OZI rule.
