By the Moreau decomposition, $x = \text{prox}_{tf}(x) + t\cdot\text{prox}_{t^{-1}f^*}(x/t)$.
If $f$ is a closed, convex function, then is it equivalent to write $x = \text{prox}_{tf^*}(x) + t\cdot\text{prox}_{t^{-1}f}(x/t)$?
This second form seems more useful for applying the decomposition to get the proximal operator of $f^*$, given $f$.