Photon scanning tunneling microscope (PSTM) images are made by scanning an optically conducting probe tip in an evanescent field above a sample surface. These images contain a mixture of topographical information, scattering effects, and variations in optical properties across the sample. Proper interpretation of PSTM images is therefore dependent upon knowledge of the field‐surface interactions giving rise to these features. The subject of this work is the calculation of PSTM image features arising from the topography of the sample surface. Image features of a model sinusoidal grating structure are calculated using small perturbation theory. Image amplitudes are shown to depend on the sample orientation and the shape and position of the probe tip. The calculated results are compared with actual PSTM images of a holographically produced sinusoidal grating surface.