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Introduction
Motion blur is normally relevant to a film camera - when a frame of the film captures an object that is moving too fast (or the camera is moving too fast), that particular frame is exposed too long to light to '"freeze" the motion of that object and so appears blurry on that frame of film. The amount of motion blur can be controlled in a film camera in two ways:
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The shutter on a film camera however is a rotating disc with an opening cut into it, called a rotary shutter, and the angle of this opening determines how long the film is exposed to light as the film rolls by the shutter. Setting the camera this way means the motion blur effect still depends on the fps of your animation because a frame of film can't be exposed longer than the fps setting of the animation, even if the rotary shutter is open during the whole frame. This means an animation running at 60fps will have less of a motion blur effect than one running at the typical 24fps for film.
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The angle of the cut in the rotary shutter determines how long the film is exposed to light. In this case the angle is 180º
In the Maxwell camera settings you can pick "Use rotary shutter" and set the shutter angle, by default 180º. Setting the angle smaller means the film will be exposed to light for a shorter time - less motion blur. You can set it all the way to 360º which means effectively there is no shutter blocking the light and the motion blur will be based purely on the frames per second setting of your animation.
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If the motion path you are getting in the render doesn't look smooth, this may be caused by an insufficient number of steps. Increase them until the motion path looks smooth.
The example below shows a sphere moving along a path. The animation lasts 30 frames and the speed is 30fps: 1 second of animation. The shutter of the camera was set to 1/1 (meaning 1 second). The rotary shutter was not used. From left to right the motion blur steps where: 5, 15, 30.
The same scene now using the rotary shutter instead of the shutter speed parameter. Left image has a 180º shutter, right image has a 360º shutter (meaning the shutter is fully open during the exposure of a frame). Even with a fully open rotary shutter, each frame is exposed for only 1/30th of a second (because the animation fps is 30) so the amount of motion blur will be much smaller than in the previous example. In this case a motionblur step of 2 or even 1 is enough.
Motionblur + Deformation
Maxwell Render can calculate two types of motionblur: for the entire object and also for individual moving vertices of the object (deformation motionblur). As deformation motionblur needs more RAM when rendering (depending on the number of vertices the object has), and is only needed if the object actually deforms, you have the choice to activate only normal motion blur or also deformation motion blur.