I can't believe this lens: It's really small, dirt cheap, has a very good construction, and it makes impressive images!! Optically I think it's better than the Oly 17mm f1.8, and it's price is just less than the quarter of it! And on top of it it's even smaller!
Very small; has f2 aperture; very high quality lens and it's dirt cheap
Not IF; but it's not a big problem