In the following assembly, ten colored balls are separated by ten panes of glass. 
Viewed from the front, through the first pane of glass, the last colored ball is behind ten
panes of glass. When rendered with the Render Quality option set to Maximum, only the
first five balls are visible, because one refraction is required for each face the light must
pass through. A setting of Maximum allows the light to pass through 10 faces. The light must pass through the front and back face of each pane of glass, so a setting of Maximum only allows the light to pass through the first five panes.
When the light cannot pass through a transparent object, the object displays as black.
However, selecting Custom Render Settings in PhotoView 360 Options and setting the number of refractions to 20 allows the light can pass through all ten panes of glass and all of the balls to become visible.
