Apertures and Vignetting

As you close down your aperture on a "Canon EF 70-200mm f/2.8L IS USM Telephoto Zoom Lens" (this is not the latest version of the lens) the vignetting disappears. 

The following images are a test I did photographing an evenly lit white board from f/2.8 to f/22. (Click on the first image to view larger and scroll through)

 

All images are the copyright of Paul D. Weinrauch and cannot be used without permission. 

                                                                                    ©2013 Paul D. Weinrauch