Grete Stern and Horacio Coppola are not household names in photo history, but an exhibition of their work from the 1920s through the ’50s at the Museum of Modern Art, on view through October 4, demonstrates that they should be. Curators Roxana Marcoci, Sarah Meister, and Drew Sawyer have drawn deeply from archives on three continents to assemble “From Bauhaus to Buenos Aires: Grete Stern and Horacio Coppola,” a magnificent exhibition of more than three hundred images, both still and moving, of breathtaking scope and quality, including vintage photographs and photomontages, advertisements, and