[chiefsilverback]

I have a K5II with the 55mm F1.4 DA* and whilst it takes stunning pictures I get a lot of 'misses' due to my kids refusing to be still for even a second and the SDM auto-focus struggling to adjust fast enough.

I'd like to get a 'daily' zoom lens that would offer a faster auto-focus and give me the ability to go wide...

I've always hankered after the 16-50 DA* but I understand that it too suffers from a slow focus speed, and the price is very off-putting, so I'm thinking maybe the Tamron or Sigma 17-50 2.8s or even the new Sigma 17-70 2.8 - 4.0. What are peoples' experiences with these?

I figure I have the 55mm for real portraits when I want max IQ but day to day I'd take an in focus child over a beautiful bokeh.

[chipa]

I asked myself this exact question recently when looking for a good upgrade for the wider end of my 18-200 cheapy superzoom. I compared both the 17-50 and the 17-70 Sigma's trying to pick a winner. The only thing I couldn't get an exact feel for was AF speed with one body to test with. But they were very closer from in store guestimates.

In the end I chose the 17-70 Contemporary for these 3 reasons:
1 - Newer model / newer technology. Who can say this wouldn't have been an EX lens a few years back?
2 - Global Vision line - e.g. I can use the USB dock to make the AF closer to perfect, if I have issues
3 - A little metadata number crunching from my superzoom told me most of my pics were in the 18-70mm range.

It's on back order, but I'm still happy with my choice.

Good luck with the choosing!

[Na Horuk]

Have you seen this review/comparison?
Pentax 16-50 vs Sigma 17-50 vs Tamron 17-50mm - Reviews - PF Blog
You are not the only one that chose to look for third party lenses in that range and avoid the DA 16-50mm. The Tamron 17-50mm f2.8 is very well liked on these forums, because it delivers great IQ for a great price and has constant 2.8 aperture.
Regarding AF, you can try things like making sure you have the latest firmware, using centre point only or using MF (with come practice, you can pre-focus where you expect the subject will be and then take an in-focus shot)

[schnitzer79]

using AF-C together with the back AF button for focusing (instead of half pressing the shutter release) works for me. a couple of months back i photographed an event called "Legion Run" which is a race with obstacles and continuous movement. I ended up using only my DA 55-300 with the method described above and not one shot was oof. and the 55-300 AF is sloowwwwww!

[bdery]

Sigma 17-70 2.8 - 4.0

I'd go with that one without a doubt. AF speed, IQ, and more than anything else convenience are its strong arguments.

However, when I read the beginning of your question, I thought about what lens I use the most to photograph kids (outdoors) and I use the 60-250 way much more than any other lens. A fast zoom could be useful too.

One last option could be the 18-135. Maybe not the best Iq (it's still fine) but very quick AF.

[cxdoo]

I recently upgraded my gear to K5-II, Tamron 17-50 and Tamron 70-200 for the same reason, namely to take better pictures of my kids. Better than the kit lens & 50-200, that is.
Even though I am perfectly happy with my 17-50, I find myself much more often shooting 70-200. Apart from it, IMHO, being special in a way 17-50 isn't, I find it much easier to have kids relaxed and forget about me when I am 5-10 meters away than when I am in their face. The only downside is that it is a very big lens.


However if you prefer the wide angles, I can only recommend 17-50. It is relatively fast (at least on K5-II) to focus, not too big, and produces very good photos.

[thechumpen]

If outside then I'm finding the 18-135 very good. It's quick and quiet with a good zoom range for handheld stuff. Any longer and you probably need a tripod. If indoors and a bit darker then it may not have a low enough F stop to capture moving critters depending on the light unless you bump the ISO up. Plus it's WR (e.g. when they're in the paddling pool etc) so all in all I think makes a good generic lens when combined with some primes for more specific stuff.

I have the Tamron 28-75 as well which is pretty good but haven't really used it since having the 18-135. I guess it all depends if you want an F2.8 lens or not...

[ChristianRock]

In addition to a zoom, you might want to check out the DA 35 2.4... it's a pretty cheap lens, very sharp and AF is fast enough I think, I use it to chase my kids around a lot. My wife uses it as well, and we get a lot of keepers.

[JibbaJab]

My Tamron 28-75 has served me pretty well for this purpose. AF works fast enough for my toddlers in most lighting conditions, and IQ is pretty good, especially when paired with flash to freeze motion.

[chiefsilverback]

Thanks for all the comments.

Re. the longer lens for shooting kids, I do have the cheap Sigma 70 - 300 but I find a very rarely use it, but maybe I'll try.

[condor27596]

I faced this problem about 18 months ago. I almost never use the zoom now. Consider zooming with your feet. The DA 21 does a lot better than the 40 pancake. Although I got a great deal on the one with the red line not the green line so it might be different not sure. My Disney shots are spectacular. I have the DA50 and 35. The 35 is more often the weapon of choice. It was cheap and it catches the action very well. I have the 77 portrait one as well.


Here is the main idea. It takes about 6 months before they stop saying daddy why are you carrying your camera again? After that, it is not noticed. You are to carry it every day, at all times, and zoom with the feet.


You want story telling without being intrusive. If I were buying one knowing what I know, it would be the DA 21. The 35 for a budget.


Zoom with the feet. After a while they don't even notice it.


Zoom with the feet.
www.turtlecreekers.org

[crossroads]

I've been looking after kids at a summer camp these past few weeks, and brought my K30 along. Initially I was using a cheap F35-70, but fairly recently acquired a DA 16-45. What I really like about the latter is how close the focus can get, no matter what focal length you are using. Them kids like to get up close and personal once they catch me raising the camera to my face.