Originally posted by biz-engineer I agree that 28 isn't wide enough in some cases, although the DFA28-105 is even smaller that a crop lens covering the same range. For the wider end, the DFA24-70 is there for someone not wanting the DFA15-30.
It's about the same as the 17-70 that cover a bit more on the wide end
But I agree with everybody there. The 28-105 is the kit lens for Pentax. The goal was to make it reasonably cheap and small too.
A 24-105 f/3.5-5.6 would need to be bigger and more expensive and a 24-105 f/4 even more!
And well if we compare other brand, there are thing like 28-70 from Sony, that far less useful in my opinion. With 28-105, you can still cover most things while finishing at 70 make you quite limited in reach for things like portraiture or to achieve any perspective compression... 105mm give you something much more comfortable.
And I think that's also the point vs the 24-70... There reasons to have both, really.
So nothing bad for that 28-105... Sure that a 24-105 f/4 or a 24-200 f/3.5-5.6 would be interresting as a 70-300 or also a 15-35 f/3.5-5.6 and a few many other focal range and apperture range to cover different needs, but it will all come in due time.