  We performed an angle-resolved photoemission spectroscopy study of the
Ni-based superconductor SrNi$_2$As$_2$. Electron and hole Fermi surface pockets
are observed, but their different shapes and sizes lead to very poor nesting
conditions. The experimental electronic band structure of SrNi$_2$As$_2$ is in
good agreement with first-principles calculations after a slight
renormalization (by a factor 1.1), confirming the picture of Hund's
exchange-dominated electronic correlations decreasing with increasing filling
of the $3d$ shell in the Fe-, Co- and Ni-based compounds. These findings
emphasize the importance of Hund's coupling and $3d$-orbital filling as key
tuning parameters of electronic correlations in transition metal pnictides.
