[mgvh]

I'm kind of thinking out loud here, but perhaps someone can help me think through this... I've followed the 16-45 or 18-135 thread, but that isn't exactly what I'm trying to figure out.

I bought the K-x with the DAL 18-55 and DAL 55-300. I love the 55-30 and don't feel a need for anything more at the long end. I was not happy, however, with the results I was getting w/ the 18-55, and I ended up buying a used DA 16-45 in the marketplace. It really was a great step up, and I found that the extra width at the short end is noticeable and appreciated. It worked out very well on a recent trip: Picasa Web Albums - Mark Hoffman - Kalambaka - M...

But...

there were quite a few times when I didn't have time or opportunity to switch lenses, and I really wanted more zoom than the 45 offered. (Also, since my K-x is not WR, I try to change lenses as little as possible.) As much as I like the 16-45, I'm thinking of trading it in for a Pentax or Sigma 17-70 or the Pentax 18-135 or Sigma 18-125. I'm hoping I wouldn't lose much quality in order to gain the greater telephoto capability.

As noted above, the width at 16mm was appreciably greater than the 18mm, and I will regret losing that width. If I go with a 17-70 or 18-xxx, I would hope someday to get an UWA Sigma 10-20 or Tamron 10-24. I do find that it is fairly easy to create wide angle views using panorama stitching in Photoshop Elements 9, even when the pics are shot handheld.

I did find a cheap Pentax F 35-70 which is very nice. Using it, I can get most of the longer shots, but I can also see how 125/135 at the long end would be more versatile. 35mm on the APS-C was not wide enough for a lot of the shots I tend to take, though. (BTW, I do also have a Pentax M 50 1.7 for my low light situations.)

I guess I'm thinking more of a walk-around lens. So, I'm mainly wondering what degree of quality I will be losing by going from the 16-45 to a 17-70 or to a 18-125/135... Will I be satisfied w/ 70 at the long end or happier overall with 125/135? I'd like, of course, to just buy them all, but the reality is that the 16-45 would have to go in order to get one of the others.

I've checked all the reviews, and the lens I've mentioned all are commended, but each does have limitations, and it's hard to make direct comparisons.

So, does anyone have experience in comparing these lens? Is there some other lens I should be considering? Thanks for any all advice you can offer!

[GeneV]

I've very happy with the DA17-70, but I might add the 18-135 to the stable before the next major trip. They serve two different purposes IMHO. The 17-70 comes closer to filling the slot formerly filled by the 16-45. It is a high quality, but not real fast option. The 18-135 is more of an upgrade/replacement for the 18-55/50-200 kit.

I find 70mm long enough for most situations. For longer, there is always the 55-300.

[dgaies]

I've owned them both (the 17-70 and 18-135), although never at the same time. I was always a big fan of the 17-70 and thought it was a somewhat underrated lens. I was always very happy with the IQ and the focus speed was very good as well. The 18-135 is also a great all-around lens. Compared to the 17-70 (form what I recall) I would say the IQ is on par, although it wouldn't surprise me if you shot them side by side to see the 17-70 come out on top. The focus is a bit better (slightly faster and slightly quieter) on the 18-135. The 17-70 is f/4 through the range while the 18-135 is f/4.5 (or faster) up until about 70mm. So over the common range, the 18-135 is almost as fast (slightly faster on the wide end, a little slower as you approach 70mm on the longer end). The size is about the same, with the 18-135 coming in a bit smaller if I recall correctly. Plus, the 18-135 is WR, which is nice if you have a WR body.

Anyway, the bottom line is I think both are excellent lens. I personally choose to go with the 18-135 as I like the extra focal length range, slightly smaller size and WR... and because I ran into a good deal on one. To be honest, if I ran into a similarly good deal on another 17-70, I might have that one again instead