With arthritis affecting my grip more each day I'm trying to lighten up the weight of my camera bag. The heavy lens in my bag is the 12-40 Pro f2.8 zoom and I already have the 17mm f1.8 and getting the 45mm f1.8 for christmas the only other prime that would complete this focal range would be the 12mm f2.0. I left off the 25mm focal length because I don't like that focal length. I realize the combination of the 12mm, 17mm, and 45mm will be 12.91 oz. while the 12-40mm is 13.47 oz. so the overall weight would be about the same but in using individual primes they would be much easier to use as far as handling weight wise although I would loose the zooms convenience. The basic question I still have is that on many forums I've read that the 12-40mm Pro zoom (@ 12mm) has better IQ than the 12mm prime. This sounds a little odd to me as I've always read (in the last 40+ years) that primes always out perform zooms. Any opinions about the 12mm vs. the 12-40mm IQ wise (@ 12mm) would be more than helpful.