Originally posted by Shanti thought is was DA* WR? main reason is to have a WR in that range for storms etc...not sure if 15mm limited is WR, but I know the DA300 is. Yes the 60-250 is on my list as well, but need a bit longer reach 1st..Have you tried the TC 2x or 1.7 on your 60-250? by chance
I have used the TC, but you have to understand the limitations of any TC. I love the TC for birds on my porch, on long distance shots, they degrade the image quality so much you'd probably be better off with a Bigma. With the Pentax 1.7 TC you're looking at F6.3. You can get a second hand 400-5.6 for a lot less, have the same reach and a much clearer image.
The 18-135 is WR, and the DC lens focussing motor is superb. Long is really a problem for Pentax right now. Frogfish and I went through the DA* 60-250 or DA* 300 F4 thing together a while ago. He got the 300, I got the 60-250. He's since moved on to Nikon equipment. There just isn't that much difference between 250 and 300. If you're not happy with the 250, you're probably not going to be happy with the 300. And the Sigma 500 4.5, is horribly expensive and heavy. The Pentax 560mm 5.6 is just horribly expensive. Pentax still needs a good lens in the 400mm range... and there's nothing on the horizon. I tried the Sigma 120-400 and the IQ was so weak in the long end over distance, I couldn't imagine myself using it, Like my 60-250 with the TC only worse, though, it was very nice for birds that were 10 feet away.