Thanks for the replies guys. I'm pretty sure I will get the 16-35 because of the fact that this lens will be only lens (16-35 or 17-40) under 50mm I need and I'm going to buy and I really don't want that F4 is the best I can shoot under 50mm. And like I said, I would never buy prime that is F4 and if I want to buy 3 primes in that same range, those would cost almost the same as 16-35 and wouldn't be any faster and wouldnt have L lens quality.