What technique did Dorothea Lang use in the migrant mother?

In "Migrant Mother," Dorothea Lange employed documentary Photography to capture the raw emotion and resilience of her subject, Florence Owens Thompson. She utilized natural light and a shallow depth of field to focus on the mother's face and expressions, highlighting her struggle during the Great Depression. Lange's technique emphasized the humanity and dignity of marginalized individuals, making the photograph an iconic representation of that era's hardships.