17-70 vs 18-250

[weatherwise2]

It's my birthday and about the 1 year anniversary of having the k10D. I want to get another walk around lens and have been reading some of the reviews of the pentax or Tamron 18-250 and it looks tempting but there does seem to be some issues at the high end.

The new 17-70 and some of the older lens of that size also look tempting.

I am now using the kit lens 18-55 and many times wish for that high end range for distant objects. I do live on the coast and many pictures are middle distance and local events or scenes typical for a "walking around" lens. I did pick up some older lens from a retiring photographer on Craig's list shortly after I got the camera and use them but none fit a good walking around glass:

M 50 mm macro f4 (my favorite)
M 20 mm f 4
M 28 mm f 2.8
DA 40 mm F2.8 (sharp)
FA 80-320 f 4.5-5.6 (soft)
M 80-200 f 4.5 (possible fungi spots on lens? Kept separate)

What are the pros and cons of the 18-250 vs 17-70mm. Do people have any issues on the high end (above 55) on either one?

[audiobomber]

Originally Posted by weatherwise2

What are the pros and cons of the 18-250 vs 17-70mm. Do people have any issues on the high end (above 55) on either one?

It will be pretty hard to compare with the 17-70 since it's so new, but above 70mm there's no comparison needed. A superzoom has some inherent compromises, notably heavier distortion at the wide end and softness at the long end. OTOH most zooms have some softness at the long end, and lens distortion can be minimized in post-processing. The biggest difference with a superzoom is that there are a lot of focal lengths in between the long and short end.

Other considerations; the 17-70 has a quiet focussing motor and Quick Shift focus, the 18-250mm creeps. The 17-70mm appears to be a more refined lens, but looking at your lens collection (you lucky dog), you already have ample refinement and some long range. It sounds to me like you're looking for more versatility in one lens, so that would favour the 18-250mm. It's clear that you find the 18-55mm too short. Another 15mm on the long end is not so much.

IME the 18-250mm is quite sharp out to 150mm, then sharpness starts to fall off. But it's still very very useable at 250mm, especially if you stop down. Here's a 250mm shot, cropped to 50% of original size:

[Alfisti]

THis is where the 18-250 makes sense IMHO. This lens is much stronger at the wide end, stronger than the kit lens anyway. Now when you consider that most wide work is stopped down (say landscapes of DOF) then the 18-250 becomes a compelling item.

I still feel the 50-200 is stronger in the overlapping ranges but at 18-70 it will push the shorter lenses very, very hard.