Standard zoom, which one?

Hi – bit of an infrequent poster/lurker on here (often find the answers without posting!) but think I could do with a bit of help on this one:

Looking to replace a Pentax 16-45, preferably with something that goes a little bit longer and is a bit sharper at the edges (my copy is pretty soft at the edges at 16mm) so my shortlist (probably used) is:

Pentax 17-70 SDM – possibly the current favourite and what I would probably have bought instead of the 16-45 if I could have afforded it at the time. Some posts/reviews suggest it may be a bit soft, whilst others call it a “hidden gem”.
Sigma 17-70/f2.8-4 – I've read similar things about this one, seems similar in quality to the above. But I think there may be two versions?
Pentax 18-135 – poor reviews, but real world users seem to like it a lot. And weather sealed. I do have concerns about the edges, would it really be any better than the 16-45?
Tamron 17-50/f2.8 – not really any gain at the long end, but reputedly very sharp. There’s also the Sigma version. The extra stop over an f4 zoom isn’t that important to me but another possibility.
Pentax 16-85 – possibly outclasses the lot, but may be a stretch of budget.

I may be over thinking this, but I tend to prefer buying once and getting it right if that makes sense (had the 16-45 for 7 years mainly used on a K10d) . I currently have a K5iis, and I suppose this may become a K3 (or something else with a higher pixel count) at some point in the future.....

Thanks in advance for any thoughts/suggestions, much appreciated!

I'd go for the 18-135mm very underated lens IMO, stopped down a bit edges aren't too bad.
I have the DA*16-50mm but take the 18-135mm when out walking, for outdoor use the 18-135mm is a great lens.

I found the 18-135 to be pretty good but I prefer the 16-85. I found it to be a sharper lens and the extra 2mm at the short end is more useful to me than the extra 50mm at the long end.

As per the first two answers, both right in their slightly different ways.

The 18-135mm will cost less and is a very, very useful lens. I use it perhaps 95% of the time.

I would go along with the answers above. My 18-135 virtually lives on my k3.

The 18-135 is much better than you'd believe from reading the reviews - it's a very useful walk-about lens in all weathers. I also have the DA* 16-50 - the image quality is better than the 18-135, but it's a lot heavier and a lot more expensive. The extra reach of the 18-135 means that it spends more time on my camera than the 16-50.

Phil

I picked up an older Sigma 17-70 2.8-4.5 on these forums and I love it. It is sharp and contrasty and is a useful range.

Mac

I've got a 16-45 and I'm a big fan. It gives great results and was on my camera most of the time.

However, I recently bought a Sigma 17-50 f2.8 OS and it's in a totally differnt league. Build quality, IQ, everything. At present prices seem to be at their lowest around £279.

Worth reading this comparison: http://www.pentaxforums.com/reviews/pentax-16-50-vs-sigma-tamron-17-50mm/introdu...

If you go for the 18/135 I would go for a new one as the early ones had teething problems

I have a 17/70 Pentax and love even though it is a little sloppy in the rings but don't let that put you of it is fast at focusing and takes a dam good photo

I asked a similar question on my post a few weeks ago about whether to buy the 18-135 or not.

https://www.pentaxuser.com/forum/topic/should-i-buy-the-pentax-18-135mm--------5...

If they have one on the Pentax stand at the Photography Show and I like it, I'll buy it.

I have the 18-135mm, it's my always on lens.

I have taken some good shots with it and can recommend it.

I always felt a slight niggle with my 17-70, and on reflection I think that was mainly down to the fact that it was my workhorse, my everyday lens ... and no one expects more from a workhorse than just dependability, right? I took the lens for granted and while I was pretty content with its results, that was the most I'd stretch to.

But, on reflection, I was unfair to the lens. I have taken (slightly) technically better photos using other lenses, but the shots that are my favourites are almost invariably from the 17-70. The photo below was taken using a 17-70, and I reckon it shows the quality this lens is capable of delivering.

link

As many have said the 18-135 is a great all-rounder - a real one-lens trip star

And if you want a fair priced S/H one for £159 then Chiswick Cameras have one...

http://chiswickcameras.co.uk/products/pentax-18-135mm-f3-5-5-6-ed-al-if-dc-wr-le...

No Connection or vested interest

How does the sigma 17 to 50 compare with the tamron?
Both are f2.8 wonder why the sigma is more expensive...

In answer to the op the 18-135 is a great walk about lens although I haven't used mine since I got the 16-85 in December....this gives better results.
Only got the Tamron f2.8 last week as I shoot a lot of darkish events and want to try with a faster lens no results to compare in detail but the few general shots I have taken have all been fine.

There's such a wide choice of zoom and speed that it really depends on I our budget and primary uses.

I've always considered the Tamron to be the best value fast wide zoom. Better than the 16-45 or 17-70 imo.
Mine is a solid performer, even wide open in poor light. It's the one I choose for astro and sometimes weddings and events if I need to be adaptable, but the photos don't exactly jump out at me. I don't think I have any that I would consider exeptional, but I think the same could be said of any of the other zooms and if I need that sort of quality, I put a prime on.