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Shutter Open/Close
The shutterOpen and shutterClose parameters in RenderSettings set the min and max time at which the shutter opens and closes. Open (min) should be less than Close (max). If min is equal to max, there is no motion blur. Moving objects will blur while the camera shutter is open.
Camera Shutter Opening
The shutteropening parameter in PrmanGlobalStatements provides control over the speed with which the shutter opens and closes. Its two arguments, a and b, are fractions of the shutter interval specified by shutterOpen and shutterClose. Over the first part of the shutter interval, from 0 to a, the shutter gradually admits more light; from a to b it is fully open; and from b to 1 it gradually closes. The rate of opening and closing is constantThere are eight fields for controlling the shutter efficiency using a curve.
To control shutter efficiency, there are eight more arguments for shutteropening, c1, c2, d1, d2, e1, e2, f1, and f2. The two points (c1,c2) and (d1,d2) specify the rate of the shutter opening motion as control points of a bezier curve between (0,0) and (a,1). Likewise, (e1,e2) and (f1,f2) specify the shutter closing as a bezier curve between (b,1) and (1,0).
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