See this post, which is self-explanatory:-
http://www.dchome.net/viewthread.php?tid=952171&extra=page%3D1
(Traditional Chinese, Google Translation into English Here)
The test shots (and crops) were made with lenses stopped down for two steps. Whilst this should not be the sharpest setting of the lenses, I think it should yet be sharp enough for this test and the purpose. In addition, the focusing accuracy of the cameras and wider open performance of the lenses could be checked.