Photometric stereo is a technique for estimating the 3-D depth of a surface using multiple images taken under different illuminations from the same viewing angle. Most existing models make use of Lambertian reflection and an orthographic camera as underlying assumptions. However, real-world materials often exhibit non-Lambertian effects such as specular highlights and for many applications it is of interest to consider objects close to the camera. In our work, we aim at addressing these issues. Together with a perspective camera we employ a non-Lambertian reflectance model, namely the Blinn-Phong model which is capable to deal with specular reflection. Focusing on the effects of specular highlights, we perform a detailed study of one-dimensional test cases showing important aspects of our method.