I have just bought this lens because I don't have any macro lens in that range, only a 55mm. It hasn't arrived yet and I was wondering if there are any "features" or good use of this lens that are worth exploring? For instance I have a PK13 and as wondering how much use that would be on the 105/4 lens? Also I read somewhere about this lens is that it has a rather good working distance. Better than the newer models, is that the case?