Originally posted by David L Nice shots!
How do you compared this lens to other Pentax zoom lenses you have used?
It's a bit hard as I haven't used them long enough and taken enough shots to form reasonable opinion (I haven't had them even one year, excluding 18-55WR and DA18-250). I don't really do "controlled" comparisons, I just want to see how they perform in my kind of shooting and compare pictures. But about image quality, I think DA 17-70/4 is best overall. Pretty good across the range and corner to corner. Most uniform. But build quality is not the best why I prefer DA*16-50 and DA18-135WR more (tighter construction). I had DA16-45/4 for a while but didn't really like the build quality and I found 17-70/4 to be better IQ wise.
DA*16-50 is pretty similar to DA18-135WR as center sharpness is excellent but corners are bit soft especially wide open. Also it's so-so at 50mm 2.8. But build quality and feel is top-notch why I like to use it. Also it has it's purposes as it is 2.8. Also it's a big lens and takes room in your bag. DA18-135WR seems to be excellent walkabout lens. I bought this to replace my 18-55WR for bad weather/hikes etc. Seems to do lot of things well. Sometimes I miss the 16mm at wide end, but obviously you can't get everything in one package. 18-55WR is pretty good and affordable but can't compete with the previous ones.
I have also DA18-250 which is surprisingly good for what it is. It does lot of things well but doesn't excel in anything. Its also quite good at long end at F8 for bird/wildlife shots. But bokeh is ugly. And top of them I have also FA28-70/2.8 which is not very convenient to use compared to previous ones as it's BIG and heavy. And also it has some retro star wars look and those buttons and clutches. But it has it's charm.
I don't find vignetting, distortion or CA big of a problem with these lenses as those are easily corrected with lens profiles in Lightroom. You may ask why I have all those lenses that cover pretty much same focal lengths? Well one reason is that somehow I find uses for them all. One reason is that I haven't really made my mind which to keep and which to sell. One reason is also that I don't believe in web reviews too much anymore. Best thing is to try it yourself and see if it fits. And when I think about it there is DA18-270 which I haven't tried but it's supposed to be pretty similar to 18-250 so I don't see any reason to be interested