Scanning tunneling microscopy has proven to be a very powerful method for real space imaging of molecules on surfaces. Here we demonstrate how the morphological and chemical structure of the tunneling tip alters the apparent topography of STM images. When imaged with conventional W tips, isolated aluminum hydride (alane) oligomers appear as 2.8 Angstrom protrusions on Al(111), When imaged with alane-terminated tips, STM image contrast is both enhanced and inverted, with alane oligomers appearing as depressions. We attribute this image reversal to the electronic levels of tip-adsorbed alanes, whose distance from the surface Fermi levels reduces the coherence in the tunneling junction. The absence of a bias dependence in these images suggests predominant tunneling through tip-alane LUMO states.