Sigma or Tamron

[RobE17]

I'm currently using a Pentax K20D/K7 set-up and in the future will be looking to add to my lens collection (who isn't? ). I have the DA*16-50 but would like to keep that for special occasions and not use it as my "standard" lens, plus it is somewhat bulky as well. I did have the DA 17-70mm until recently, I had to sell that but also in comparison to the DA* I found that the images were not as "punchy". So I would be looking for is a lens that has comparable IQ to the DA* 16-50mm but perhaps is not so large.

I think the alternatives would be:

Sigma 18-50 EX F2.8
Tamron 17-50mm F2.8
Sigma 17-70mm (new/old version - I have read that IQ is better than the DA*16-50mm??)

Not concerned about lack of SDM or weather sealing to be honest as I can always use the 16-50mm if the conditions dictate, just which one would offer comparable IQ.

Any ideas, suggestions, feedback, etc would be greatly appreciated.

Thanks

Rob

[Dorset_Mike]

I've ben using the Tamron on a Minolta 5d and Sony A350 for over 2 years, very satisfied. F2.8 throughout the range, sharp, not too heavy. Some people slag off plastic bodies, this may have been valid back in the 1990s but not now.

[El_Sid]

I have the original version of the Sigma 17-70 (sans HSM & OS) in Canon fit and have been very pleased with it's performance. I would be very surprised if the current version is any less able. If your cameras have built in stabilisation and can live without HSM then you may get a good deal on the older version.

Can't comment directly on the other two but both have recieved equally positive testimonials from various members of the forum.

PS

FWIW here's an example of what the 17-70 can do.

[IvorETower]

I've also got an older Sigma 17-70 and it's probably the sharpest, best-performing zoom lens that I have got. I'm truly delighted with mine, especially as I got it in a clearance sale a couple of years ago for under £100

[chr1s]

i've got the tamron 17-50 f2.8 and i think it's great. solid enough, sharp, focusing is accurate and reasonably quick. i got mine secondhand from camtech, but even at full price it's a good value lens.

[jeallen01]

Just a minor issue - maybe if you use manual focus a lot:

Typically, in manual focus mode, Tamrons barrels have to be rotated one way and Sigmas barrels the other! Can be very annoying if most of your lenses rotate one way - but one rotates the other!