Originally posted by mk19 I would like to know why Pentax would spend time to redesign this lens if the improvements are to be insignificant in real usage.
I think the main issue is that the limitations of the 18-55 were kind of holding back the image quality of the K20D a bit. Really, the K20D is not that different from the K10D - *the* big difference was the sensor. And the limitations of the original 18-55 were not showing off the new sensor quite well enough, so they tweaked it some.
So I'm not saying there are no improvements. I'm saying they are pretty hard to see, especially if you aren't using a K20D. The new kit lens will take pretty much exactly the same pictures as the old, just maybe with a little better corner resolution at some focal lengths and apertures, etc. Whereas the FA50/1.4 would let you take pictures neither kit lens could *possibly* take - both because of it much wider maximum aperture, and because it is a *very* noticeably sharper lens.
So if you already have a perfectly good 18-55 and are looking to spend $100 to improve your photography, replacing the 18-55 with the 18-55 will make a *tiny* difference in your photography. You'll take the same picture,s but corner resolution will be marginally better. Whereas if you get the FA50/1.4, that could easily make a *huge* difference in your photography. Ditto with any other lens that is more, well, *different* from the original 18-55 in either speed, focal length, macro capability, etc.
Here's another way of putting it: if you are currently using a UV filter on your 18-55, the improvement you get simply by taking that off are probably at least as big as the improvement you'd get with an 18-55 II.