A vision system useful in acquiring images includes: a light dome having a window and a perimeter; an annular light curtain positioned within and radially inwardly from the perimeter of the light dome such that an annular gap is formed between the light dome and the light curtain; and a light ring positioned to illuminate the gap between the light dome and the light curtain. The light curtain and window are sized and positioned such that no direct light from the light ring reaches the window. The system further comprises a camera having a lens facing the window to acquire images of an object on a side of the window opposite the camera. The images acquired by the camera can then be compared to stored images to determine whether the identity of the objects (which may be pharmaceutical tablets) is as expected.