Hello! Anyone has experience with the Sigma 30mm f/2.8 coupled with the Panasonic GH2? I could buy one, mostly new, for 150$. So basically, I'm saving the taxes (15%), import/duty fee of a new lense bought from B&H. Would that be a good complementary lense for my Panasonic 14-140mm f/4-5.6? or is it too similar? I'd get a higher aperture (f/2.8 vs f/5 at 30mm). Thanks! PS: I don't have enough money for a pricier lense. At least, not over 200-250$.