HI May i lfited the sky out because i wanted to see the definition of the leaves, and the DOF, then applie hue/saturation to it to get the look I desire, I think it has worked ok. at 28mm or 200mm I have not seen any artefacts, well not with my lenses, but then all mine are canon and sigma, so not really looked at the approved list as yet but will do later and see whats good and whats not john (UK)