Too much whining about "not enough lenses".
Especially so from theorists who don't really have the camera or lenses.
Actually to the naysayers using this argument, its more like "do you have the $"
I have tried the DFA15-30, 24-70, 70-200.
They are very good indeed.
DFA15-30 for example is sharp to the edges for landscapes.
A match for anything out there.
Just need to pay up......
It may sound blunt, but any good IQ UWA to wide combi with AF (often without), will cost.
Don't even get started with the "but the original Tamron costs less ".
From the ephotozine review, the DFA had better edges.
Pentax may have asked for very tight test specs for their version of the lens.
Canon went thru 4 versions of a uwa zoom to get to the current good one (ie. EF 16-35 /4 L)
17-40L, x2 16-35/2.8L were not great on the edges.
The DFA15-30 is right, straight off.