a quick question... I noticed how the 90mm Elmarit had pretty slim depth of field at f/2.8. So, if f/1.4 on a m4/3 sensor feels like f/2.8, then can the same math be applied to longer focal length? If I do my math right, 90 @ f/2.8 should give me similar result like a 50 @ f/1.5? It sure feels that way. This is all excluding the light-gathering-ability, of course, strictly talking about DOF.