I missed this the first time around!
At the moment I don't have what I would consider a dud lens.
Pentax DA 16-45 F4-Sharp and the only thime I have any ca is when it is really bright out and seeing as how most of the time I use it is very early morning light it is a non issue.
I have a Sigma EX 100-300 F4-Great lens. I wish it was longer but within range it is fantastic.
When the 100-300 isn't long enough I have the Bigma
Vivitar Series 1 105mm f2.5 macro. Cult classic, super sharp and great rendering.
The 2 telephotos are for one type of shooting, the 16-45 for landscapes and the Vivitar for close up stugff and flowers.
I was holding off to see what the K20 was like before I bought the Bigma. I wasn't ever really ecstatic with my K10's focus. It is at Pentax for a factory cal right now. I have read that persons that sent them in since the K20 came out have been very impressed with the focus after the factory got done with it. I'm hoping.
I want to buy some primes this year, too. I'm just not sure which one. When I go back and look at my shots with the 16-45. I end up with a bunch at 24mm. So what is a good 24mm lens. I know there is a FA*24mm F2 but those are astronomically priced used. I'll probably try to find a nice A 24mm f2.8.