Four years later he had become the senior apprentice of Johann Phillip Veith, who himself had learned landscape drawing and copper etching from Adrian Zingg at the same establishment.
In 1816 Hammer became an academy member, joining the famous circle of Dresden Romanticism, accompanying the likes of Caspar David Friedrich and Johann Christian Klengel.
Hammer's works are extensive: including his own designs in sepia, watercolor, and opaque colors, and also copper etchings from his own drafts and those of other artists, such as Caspar David Friedrich, Gottlob Friedrich Thormeyer, Johann Clausen Dahl, Georg Heinrich Crola et al. His works consist primarily of landscapes and city views, particularly in Saxony and his home town of Dresden, and the vicinity.
An 1810 volume printed by Carl Christian Meinhold had prompted a great deal of interest in Dresden at that time.
Hammer was one of the first painters to discover the pristine water world of the Spreewald; he created several high-romantic pictures of this unique European landscape.