No need bud

2 ways, both done in post rather than in Maya.
(best to always to dof blur in post cause you have way more control)

WAY 1: (cheap and easy)
Make a tighter, less "gradual" radial gradient around your frog in your compositing app, then track it to your frog and use it as a dof blur channel.


Way 2: (what I do most often)
Grab the YUYA DEPTH SHADER from the shader section off another "highend" 3d website, hehe, then when you've completed rendering your Maya scene, save it as a depth.mb file, then select everything and apply that shader to all.
It will "simulate z-depth" distance from camera at render-time for you without having to mess with the cam settings.

Hope that helps ya a bit