### Change perspective viewpoint to infinity in 3d plot

I am plotting a function with a large z coordinate, so it has a rectangular solid box around it which is square in crossection and very long in height. If you rotate it to view from the end you don't see the orthogonal projection onto the square, since the solid framing the graph is rendered inperspective from a viewpoint which is not infinity.
I tried aspect_ration {1,1,1] but that doesn't correct it. Any ideas ???