[Christine Tham]

Would like to buy a telephoto zoom to go with a planned K-5 purchase.

Intended use - sports, wildlife, some portraiture

Trying to choose between (all at constant f/2.8 across zoom range):
Pentax DA* 50-135
Sigma EX 70-200 (non OS)
Tamron 70-200

Any thoughts?

I like the longer throw of the Sigma and Tamron, but like the WR of the Pentax.

I heard there are focusing issues with all three? Maybe fixed on the latest Pentax units?

All seem to around the same ballpark in terms of price, with the Pentax being slightly more expensive.

I like the macro of the Sigma, but I can get a macro attachment filter for the Pentax.

[blackcloudbrew]

I own the Pentax 50-135 and Tammy 70-200. I'm glad I have both. The Tammy is just a big sucker that while is a little slow focusing, really rocks. The Pentax is such a nice lens and is of course smaller and lighter. At times it's a bit short but then at times the Tammy is not short enough. The Tammy has one nice feature that it's a full frame lens and works very well on film bodies.

In use, I'm finding that the Pentax gets a bit more use.

Honestly, with your stated intent, I think the 70-200 range would be more useful. I've not done portraiture with either lens by the way. If I did, I'd use other lenses but I've read that the Pentax is the better of the two for that, mostly because with a cropped sensor you may want to be working below 70mm.

[pbo]

DA* is the lightest and the smallest, especially if you use it without the hood - it looks like Nikon's 24-70, for comparison.

I've heard Sigma's lens have softness issues at longer focal lengths (I had a non-HSM version, which was fine, plus it focused super-fast). Very heavy and big, when compared with DA*.

Tamron had aperture mechanism issues, not sure if that's relevant now. Expect it to be big and heavy, though

[DSims]

After I realized most of my good shots with my DA55-300 were between ~50 and 135mm, I chose the Pentax DA*. The 50mm end is really useful - when a wider shot opportunity comes along and you realize you're "stuck" with a telephoto zoom mounted, 50mm is usually wide enough to still get something good. I also believe the DA*50-135's image quality can't be beat in a zoom, although many others like the Tamron and Sigma (I don't so much).

I think it may come down to which zoom range you really need. I may add a 70 or 80-200 fast zoom someday, but right now I just pull out the 200mm MF prime (K200/2.5) when I need to go over 135mm. For your intended use, you'll have to figure out which focal length is better. You may well want at least a 200mm or 300mm prime in the future.

[LenWick]

I only have the tamron - both shots below taken with it

squirrel | Flickr - Photo Sharing!
Miki 39 weeks | Flickr - Photo Sharing!

I had the aperture issue within a week of purchasing the lense - got it fixed under warrantly
It is now in for focus issues - which should also be under warranty too - from other users it sounds like once you get the kinks out it's a great lense. But I keep wundering if I should have saved my pennies for the pentax 60-250 -

I love the lense when it's working, but I usually end up using medium telephoto primes for portraits, unless I want the field of view at 200mm then I switch over.

[Arpe]

For field sport 135mm is too short by far, even 200mm is, which is why I generally use a 1.4x TC as well. So buy the Tamron or Sigma and a plastic bag.

[Ubuntu_user]

Well, I've had both the Sigma and Tamron that you mention. What I ended up choosing? The Sigma 50-150mm. It's IQ is at least that of the Tamron if not better (some people around here say it matches the DA* 50-135mm).
I use it primarily to shoot sports (field and indoor) and it simply blockbusts. Stellar. Very solidly built, and the 50mm end comes in handy way more than I would have guessed. My copy of this lens seems to have no performance drop off at the tele end, of course YMMV. Overall, there's only been a couple times when I've wished to have the extra 50mm, but the IQ of this lens makes me quickly forget that.

[psychdoc]

Intended use - sports, wildlife, some portraiture

I can only comment on the 50-135 with some conviction

Portraits: Great for this application!
Sports: depends on the sport. Short for some types of sports. For basketball and volleyball that I shoot it is good within limits. But I rarely print photos and often I shoot wide and crop and its good enough for me. Also I just shoot my own kids playing and I can get pretty close. Lighting is atrocious and the k5 really helps. AF speed on this lens is not supposed to be that fast but I guess I am living in blissful ignorance since I have no experience with faster AF lenses.
Wildlife: too short.

70-200:
Only used the tamron. Too big for me. Looks ugly too! The 50-135 itself tires me some when shooting games...I would not want to carry anything bigger.

P.S: some people consider the 50-150 from sigma as a viable alternative to the pentax 50-135, especially if u are worried about sdm.

[Christine Tham]

Thanks for the replies everyone, much appreciated.

After reading them, I'm leaning towards getting the Pentax.

Are there any teleconverters that would work with it?

[JHD]

Thanks for the replies everyone, much appreciated.

After reading them, I'm leaning towards getting the Pentax.

Are you sure? Another cat just coughed out an SDM hair ball.

READ... https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/130049-f%2A%2A...aar-shoot.html

SDM failures are so prevalent they may as well be classified as inevitable.

[dgaies]

Are you sure? Another cat just coughed out an SDM hair ball.

READ... https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/130049-f%2A%2A...aar-shoot.html

SDM failures are so prevalent they may as well be classified as inevitable.

Prevalent? Yes, certainly at a much higher rate than screw driven lenses which are extremely reliable.

Inevitable? I doubt the statistics support that the failure of SDM lenses is literally inevitable.

But your point is noted; you hate SDM lenses and would encourage anyone thinking about buying one not to do so

[Ash]

You can't go wrong with the 50-135, Christine.
It's probably the best acclaimed DA*
Few owners have had much negative to say about it.
Unfortunately, you may find the 'compatible' TCs such as the Tamron Pz-AF 1.4x TC giving you less reliable focus locking, but there have been reports here of it doing alright.
I do know that with the Sigma 70-200 HSM version, the TCs with HSM/SDM compatibility just cannot get the lens to lock focus at any focal length greater than 180mm on the lens, even in perfect lighting conditions. A significant setback.

Do some more research on that, particularly on the forum archives, and make your decision accordingly. But if it were me, and you wanted more reach than 135mm, I'd go for the Tamron 70-200 with 1.4x TC or DA* 60-250 (which is very versatile and also weather sealed, but considerably bigger than the 50-135).

[psychdoc]

Are there any teleconverters that would work with it?

If you are looking at TC's then it means you are really wanting a longer reach. Might as well get one of the 70-200 f2.8 lenses then instead of fooling around with TC's and poor quality...