Quote Originally Posted by Pavel+ View Post
... In the diagram you show, light will correctly illuminate a wider field in the last example - but it is immaterial as it will miss the film and thus not affect the angle of view. ...
The only point of the diagram is to show that too thick of a pinhole material can cause vignetting. The caption states:

The pinhole material thickness limits the angle of coverage. Thick materials may reduce the angle of view, and the pinhole will no longer fill the entire negative format.

Sorry, if I didn't make this sufficiently clear.