The diffuser box is a "soft box", but still the light gets condensed by the Leitz condensers. I've seen solutions where someone built a diffuser which should replace the condenser of the Focomat. (If I recall correctly it consisted of probably 3 layers of opal glass.) While the results were acceptable they had totally lost what I personally interpret as the "Focomat signature". I.e. (still in my mind) they were softer in both sharpness and contrast.
Originally Posted by youngrichard