I have a book titled: Andreas Feininger Photographer (Harry N. Abrahms Inc, NY 1986- ISBN 0-8109-0919-7) author was Feininger.
It is basically a coffee table autobiography that contains a great number of images covering all aspects of his career.
There are photos and a description of a 4x5 camera he built that allowed for extreme telephoto shots.
"I combined a retired 4x5 view camera body and a boxlike wooden extension tube and equipped this contraption with a Dallmeyer Grandac variable-focus telephoto lens set at a focal length of 40" which I picked up at the odds-and-ends counter of a large photo store"
He also discusses inventing a "five-pod" to keep the 2 and a half foot long monster stable. He does not use the term "big Bertha" but i would guess that this is the camera you are curious about.