He found a patron in Ferdinand von Plettenberg, who took Krahe along when he was appointed Imperial Envoy to the Papal Court in 1736.
In 1749, upon the recommendation of Silvio Valenti Gonzaga, the Cardinal Secretary of State, he was pensioned to Charles Theodore, Elector of Bavaria, on whose behalf he painted altarpieces for the Jesuit Church in Mannheim.
Eleven years later, his school was designated the "Electorate of the Palatinate Painting, Sculpture and Architecture Academy" (later, the Kunstakademie Düsseldorf) and Krahe became its first director.
Begun when he was in Rome, and expanded during travels throughout Germany, Holland and France, it came to include 332 paintings and oil sketches, as well as thousands of drawings and prints from the 15th to 18th centuries.
The collection also includes woodcuts by Albrecht Dürer, engravings by Martin Schongauer and etchings by Rembrandt.