Even 5% is not the limit now if the figures from - say - the new Tamron 20/2.8 are anything to go by (8,1% barrel as measured by Ephotozine for their review); the 24/2.8 isn't far behind.
(EDIT: I was replying to toni-a but I was so slow that Markus got his post up in the interim).
(EDIT: I was replying to toni-a but I was so slow that Markus got his post up in the interim).