Set motion blur in mental ray for Maya
 
 
 

When you render an animation, motion blur gives the effect of movement by blurring objects in the scene. For more information on motion blur, see Focus and blur.

mental ray motion blur specifics

Supports only 3D motion blur.

To set motion blur, in the Quality Presets section of the Render Settings window set Quality to an option that includes Motion Blur, then work with the settings in the Motion Blur section of the Render Settings window.