I am using red-colored Photina foliage,backlighted by the afternoon sunshine,as my out of focus background material in an effort to see how this Canon 100mm macro lens renders such foliage. HEre, at f/5, it is clear that the sharp-sided diaphragm shapes are very much back....I really do not like the way this lens is handling the OOF backlighted foliage,introducing a LOT of diaphragm blade shape to the highlights themselves,making them look clearly angular and artificial.