For Maya software rendering only.
Try the following:
The background is also blurred in this case even though it should not be. The solution is to blur the transparent object separately and composite with the rest of the scene. This workaround can be difficult for complex scenes with lots of transparency, or for transparent particles.
Some details may be lost because assumptions must be made about the background area occluded by the moving objects. The solution is to blur the moving objects without the background and then composite the results.
May not look exactly right, because assumptions about what the back sides of these objects should look like must be made. Try using 3D motion blur.
The edges of frames may not get the correct detail, because assumptions must be made about the object color that is just outside a frame. The solution is to render a slightly larger image which covers the original image and then crop it to the desired size.
Try not to mix the rendered images from two different kinds of blurring operations.
When tuning 2D motion blur with IPR, automatic updates are not always done correctly. Tune an attribute of a material or light to force a correct update, or marquee the tuning region to force an update.
2D motion blur can cause artifacts when rendering in scenes with fog, or solid objects in front of transparent ones, or if the background color is not black.
There are three possible workarounds: