  A new method for measuring the shear induced by gravitational light
deflection is proposed. It is based on analyzing the anisotropy induced in the
auto-correlation function (ACF) of the extragalactic background light which is
produced by very faint distant galaxies. The ACF can be measured `locally', and
its anisotropy is caused by the tidal gravitational field of the deflecting
mass distribution in the foreground of these faint background galaxies. Since
the method does not require individual galaxy detection, it can be used to
measure the shear of extremely faint galaxies which are not detectable
individually, but are present in the noise. The shear estimated from the ACF of
the noise provides an independent measurement which can be compared to the
shear obtained from the distortion of individual galaxy images. Combining these
two independent estimates clearly increases the sensitivity of shear
measurements. In addition, our method may allow to determine the local
magnification caused by the deflector if the auto-correlation function is
caused by a large number density of faint galaxies; in this case, the intrinsic
ACF may provide a `standard source' with respect to which shear and
magnification can be obtained. Applications to real and synthetic data are
shown and the feasibility of our new method is demonstrated. In particular, we
present the shear maps obtained with our method for the double QSO 2345+007 and
the cluster Cl0024+16 and compare them to published shear maps.
