Originally posted by HelenJo If there is anything someone would like to contribute with my choice ? Please feel free.
I feel confident in it , but there may be something I havent considered.
It's a superb lens, and has been my most used on APS-C more or less since it was released.
On some no longer fresh bodies (e.g., K-50), there could be issues with PDAF (viewfinder) focus at wider angles.
This seems to be the root cause of some early testers' negative attitude to the lens.
(That, and the fact that it wasn't the Sigma 18-35, which was the big excitement at the time.)
So I normally used CDAF from live view to focus it when zoomed out to below 30mm.
My newest APS-C body is a K-S2, where I still tend to use the CDAF technique.
However, I've recently been trying the DA 20-40 on a K-1,
and that camera's more modern PDAF seems to cope better.
So you may not need to worry about this on your KP.
But if the wide end does look soft, you could try using live view to focus.