Linhof Multifocus Viewfinder Question

Linhof makes a zoomable viewfinder for use on technical cameras, which they call their "Multifocus Viewfinder". For those of you familiar with it - does it provide a true optical zoom? Or does it simply elongate when you zoom, like several cheap directors viewfinders, and present you with a tunnel vision view of the world?

I'm not sure if I'm making much sense, but in a true optical zoom, the image thru the viewfinder would stay the same size as you zoom, but the field of view would change.

Thanks.