I've been reading a lot about the Pentax DA 18-135mm lens and its performance compared to other lenses. I've heard that this lens is very soft at 135mm regardless of aperture. However, I've also read that the image quality is overall better than the 18-55mm lens. I am confused about the performance of the two lenses as a result. Since I own an 18-55mm lens (came with my Pentax K-r), how does the image quality of the 18-135mm lens compare to the 18-55mm, especially wide open in the edges and corners? Is it better or worse than the 18-55mm in terms of resolution?
It's a pretty decent lens, despite what the Photozone review says. You've already seen the Pentax Forums review that includes crops of a chart. I'd trust your eyes over what some chart with numbers on the web says.
I've had the lens for a few months, and it's softer in the corners at the telephoto end compared to my DA* 50-135mm. Despite that, the 18-135mm lens is my most frequently used lens as it's "good enough" and it covers a very useful range.