After leaving school, Kehrer received a scholarship from the Graf of Erbach-Erbach, Franz I., which enabled him to reside in Würzburg from 1793 to 1797, where he studied under the court painter Johann Christoph Fesel [de] (1737-1805).
After a brief time at Saarbrücken in the court of the Herzogin of Braunschweig-Bevern, he returned to Erbach where he was employed as the private secretary of the Graf, who recognized his talent as a painter and encouraged him.
[1] Kehrer maintained his connections to Erbach and its ruling house throughout his life, though he fell out favour in 1820, when he pointed out to the Graf that the Roman legionary eagle found near Würzburg was a blatant fake.
King Friedrich I. of Württemberg commissioned Kehrer to create paintings for his hunting lodge in the grounds of Freudental Castle [de].
[4] Around 1861, Kehrer made a partial copy of an illustrated manuscript from the middle of the 15th century from the former estates of the Graf, which is now preserved in the National Museum of Germany located in Nuremberg.