Originally posted by Saxplayer1004 All I've read and witnessed, albeit only on Nikons, is that the overall quality of the Tokina 11-16 was significant better than the 16-50 and the 50-135. The 16-50 was the worst of the bunch, plagued with softness etc, but the 11-16 put the Canikon equivalents in their place for less than half the price. Again, just saying that from what I've read and since my cousin had all 3 at one point, ended up selling the longer 2 recently in favor of Nikkor lenses, but the 11-16 stayed and it is a truly fantastic lens.
The overlap in focal length doesn't necessarily matter if they are in different lens classes though. To have a full on 2.8 line from UWA to telephoto for professionals etc is great, then to have a full F4 line for those who don't want to shell out for the 2.8's either in $ or in size/weight, then it isn't overlap, it is merely an alternative line of lenses. If you look at Nikkors lineup, you can see it. 14-24, 24-70, 70-200 all 2.8's, then the 200-400 f4. Then the option with the 16-35/4 if you don't want the extra weight and bulk of the 2.8, the 24-85 2.8/4 and the 70-200/4 for the same reason. Sure it's overlap, but when the constant 2.8's are twice the size and weight, it is all about having the right option for the right occasion.
That's a plus for being on top...you have the capacity to make multiple versions of the same focal length. Unfortunately i dont think Pentax has the capability to do that. So Pentax has to be a lot more judicious how they use their resources.
But looking at it from a consumer point of view, yes, it would be awesome to have the option of going full pro with a f2.8 zoom vs being a lil cheaper and getting a f4.