Originally posted by Biff Thank you both. I'm thinking of ways to simplify and the 16-50 PLM would go well with the 11-18, and I don't think I need two zooms in the 16-50 range, but the 20-40 is so nice and compact (and looks so good on the KP) it would be hard not to keep it.
I've had my DA 20-40 Ltd for quite some time, got a great deal on a new one. Got it in silver by choice BEFORE the KP came by around a year, thinking "someday Pentax will come forth with a great compact body available in silver like some of the old 35mm AF bodies they used to make". I must have had some kind of premonition. I initially used it on my compact K-S2 with great results. Then about 2 years later, after the price settled down, I got my first silver KP, then some time later, got a 2nd one- that is how much I like it.
I later acquired a Sigma 17-50mm f/2.8 EX DC HSM lens. Its DC is not as fast as PLM, but is quick enough for me and very accurate on my KP, and the lens delivers very fine imaging. But these f/2.8 constant aperture lenses have to be bulky and heavy. So I use this lens when need what only it can do. It makes a great match with my DA* 50-135mm f/2.8, an amazingly compact lens, but so does my DA 20-40mm Ltd when I do not need f/2.8 all the way through. Most of the time, I carry the DA 20-40mm Ltd on my KP and get very fine imaging. It seems to fit like a custom-made glove. This makes for an extremely capable compact outfit. I would not want to be without it. To get a real-world actual view of what it can do, go to the Imaging Resource test. Go to the bottom of the test which displays a still life test image and click on this to get a blowup. Then you can select wide open or stopped down at the wide, mid, and the 40mm end. Click on any part of the image, including close to the edge where the circular numerical scale and brush are or down near the bottom, etc. There are many spots to check sharpness, like the Roman figure on a bottle, or another figure on another bottle, etc. I think it shows very impressive performance compared to other lenses.
Bottom line- both of these lens types have their uses in practical terms, and in terms of what a wider aperture can do. With me it is not a case of either/or.