  The first images of black hole shadows open new possibilities to constrain
modern extended gravity theories. We present the method of shadow background
calculation for black hole solutions in the form of Taylor series where $g_{11}
= - g_{00}^{-1}$. The method is extended to general non-rotating case $g_{11}
\neq - g_{00}^{-1}$. The results of the analysis are compared with the
predictions of General relativity taking into account the Event Horizon
Telescope data. The results for the Horndesky model with the Gauss-Bonnet
invariant, loop quantum gravity, Bumblebee model and Gauss-Bonnet gravity are
in full agreement with the observations of M87*. In conformal gravity, large
values of $m_2$ and $Q_s$ must be excluded. In STEGR $f(Q)$ gravity the
observational limits on the parameter $\alpha$ are: $-0.025<\alpha<0.04$. For
an alternative generalization of the Bumblebee model with the Schwarzschild
approximation: $-0.3 < l < 0.45$. These results demonstrate the maximum one can
achieve without taking into account of the rotation of a black hole.
