thanks for replying
this sounds totally logic and the postcard example visualizes this perfectly.
but do you see a way of solving this problem with expressions. like reading the camera movement from frame to frame and calculate velocity and direction and map them onto a directional blur on the 2d layer.
the easiest way is definitely to render motion blur out of the 3d app, but somehow i thought that there is a faster and therefor more controlable way in post.
jakob