I think it was just at that time that Leitz made an agreement with Minolta for the realization of their first zooms (based on Minolta designs). Leitz being a small, quasi-artisanal firm did not have or could not afford a research centre able to deal with the new design tecniques, I imagine. Computer-aided design made zoom lenses possible for photographic purposes. Until then they were basically only seen in the motion picture industry or in small movie cameras. "Turrets" or "bifocals" were the alternatives.