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Motion blur can be enabled in the Render Settings window under the Features tab.  By default it is not enabled. The dropdown menu also gives you the option to output 2D motion for compositing operations.

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Shutter Timing

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Shutter Timing Shutter Timing

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Our red ball looks kind of odd in the second frame with centered blur.  The blur is horizontal, when the ball really should reach an apex in the middle of that streak.  By default, there are only two motion samples, because they are expensive, and two is often sufficient.  You can change the global number of motion samples in Motion Blur section of the Render Settings. Or if you know that only a particular piece of geometry requires extra samples, you can add them to just that geometry .  Select the geometry, and in transform.  

In the Attribute Editor , under the transform tab for the selection, do Attributes->RenderMan->Add Motion Samples.At the bottom of the Attribute Editorfor the transform, with tab for the sphere's transform selected, you'll see a setting for motion samples. -1 is the default and inherits the global setting.

Two samples means that the position of the ball is sampled only at the shutter open time and shutter close.  More than two samples are evenly distributed between shutter open and close.  This is sometimes referred to as Multi-Segment motion blur.

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Spends the whole interval opening, then closes instantly at the end.

The Shutter Opening settings that appear in the Render Settings affect any camera that you render with.  You can alternatively apply specific shutter opening settings to a particular camera.  To do that, select the camera. (View->Select Camera).  In the Attribute Editor, click on the shape tab for the camera, and do Attributes->RenderMan->Add Shutter Controls

You'll see the settings appear at the bottom of the Attribute Editor window:

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Shutter Angle

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ShutterAngle ShutterAngle

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