Variable motion blur is created by varying the evaluation time used to determine the poses of objects according to motion blur parameters when evaluating a blur frame. A blur parameter can be associated with one or more objects, portions of objects, or animation variables. The animation system modifies the time of the blur frame by a function including the blur parameter to determine poses of objects or portions thereof associated with the blur parameter in a blur frame. The animation system determines the values of animation variables at their modified times, rather than at the time of the blur frame, and poses objects or portions thereof accordingly. Multiple blur parameters can be used to evaluate the poses of different portions of a scene at different times for a blur frame. Portions of an object can be associated with different blur parameters, enabling motion blur to be varied within an object.