What is the difference between these two lenses? B&H in NYC has the original for under $300 right now (probably selling off remaining stock) and the II is almost $400. I will be using it with an OM-D E-M10. I have read that this camera now has CA correction, will that work with the Panasonic lens? I'd prefer the Zuiko 12/2.0 but it's twice the price for only a half stop faster and a few degrees wider angle.