
Originally Posted by
Mike Buckley
A more scientific way to think of the tones in the image, Christina:
Assume (inaccurately) for purposes of simplicity that there are only three tones in the images -- white, grey and black. When photographing clear glass, everything that is white is where light is either passing through the glass and we are seeing only the light (with nothing reflecting it) or it is the light being directly reflected by the glass. (The term, "direct reflection," simply means that the light source itself is being reflected. The reflection is always a mirror image of the light source.) Everything that is black is where no light is falling on that part of the object. Everything that is grey is where some of the light is falling on the object but not so much that it appears white and not so little that it appears black.