In 'Lens Matters' I have asked the question about lens resolving power and more densely populated sensors. I have noticed a small drop in image quality between the images taken with this lens on my K10D and now the K-7. It is not the camera, as I get excellent results using, for example, my Pentax 100mm f/4 macro lens. I am looking for a higher resolving lens in a similar range, but which one? The Pentax 17-70 f/4 does seem to have limitations and slight distortion problems, so perhaps it is not the one to go for. Any suggestions are welcome.