Camera 

Specifies how many motion blur steps to use for the camera. It makes sense to increase this value for cameras that are moving rapidly and following a non- linear path.

Transformation

Specifies how many motion blur steps to use for transformation motion blur. It makes sense to increase this value for rapidly rotating objects such as a car’s wheel.

Deformation

Specifies how many motion blur steps to use for deforming objects. Unless an object has an extreme deformation movement, this value should be set to 1. Having more deformation steps is more expensive (in terms of memory usage) than having more transformation steps since this implies geometry duplication inside the renderer.