Sigma 24-70 EX DG vs. Tamron 17-50/28-75

I found a cheap copy of the older non-HSM version of the Sigma. It is going for $350. I was curious if this was a better lens than either of the Tamron's (17-50 and 28-75). I was leaning towards the 17-50 before because I do not have a wide angle lens, but the build is quite a bit better on the Sigma. Any thoughts?

If you don't have anything wider than 50mm, I'd recommend the Tamron 17-50 f/2.8 over the Sigma 24-70 DG EX Macro (i.e. non-HSM model).

The Sigma will still be a faster focusing lens than the Tamron, but the difference between 17 and 24mm is quite substantial and on a 40D, this would be the deciding factor for me.

I recently was in the same shoes finding a normal zoom to pair to my 70-200 f/4L IS, and was considering the 24-70 DG EX HSM (because I liked it better than the 24-70 f/2.8L USM) and the EF-S 17-55 f/2.8 IS USM and the Tamron 17-50 f/2.8. For me, the slower focusing of the Tamron made me go for the Canon EF-S 17-55 f/2.8 IS USM (the IS was a big added bonus, but of course the price was a lot higher too). I don't consider the gap from 55mm to 70mm as much of an issue as the gap I would have had from 16mm to 24mm (which is much more prime FL real estate, at least for me).

Thanks for the info. I was kind of thinking the same thing. It would be nice to have a wide angle for once (I started out with a 28-135 and sold it, have been sportin' the nifty ever since due to financial difficulties with being a full-time student married to another full-time student with a child). I finally have a little bit of money to spend on a couple lenses, so I want to make the right choice.

Any other opinions/recommendatio​ns appreciated.

+1 for the 17-50 if you don't have anything wide. I would also recommend if you wanted to save some cash, the 18-55 IS (kit lens) would be a good choice to look at as well. It doesn't have f2.8 but the IS helps bump it's value a bit.

I personally chose the 28-75 from Tamron since I don't find myself going wide often and I have the kit if I need 18. So far (I got it on saturday) it's been a great lens, the AF speed is pretty good too (although not USM speed).

Owned the Sigma 24-70 EX and now the Tamron 17-50

I previously owned the Sigma. I need a good lens to shoot a indoor shoot.

The sigma did not disappoint, it was a sharp lens at F4 at all focal length. At F2.8 it was not bad either just a little softer towards the leng end that sharpening could not fix.

After I did the shoot I did not use the lens so I decided to sell it. The lens is built sturdy and its heavy.

I read the review and saw many samples of the tamron and decided to give it a try. My first copy with the body 40D had a front focus issue. Went back and swaped it at the store for another that was perfect.

A proper calibrated tamron to the body can yeald very sharp pictures with excellent colors and contrast.

I found that indoor a 24mm might not be wide enough. The 17mm on a crop is nice gets you some good landscape photos.

Here are some samples of the tamron. I went to Chicago and decided to try the 50D and the tamron. Right out of the camera with camera sharpness at 4 all the shots were taken at F5.6 no need to step this lens down beyond.

Pics look good! 17-50 it is...

I just got a 17-50 Tamron for my 50D. I was a bit disappointed in the focusing consistancy. On my test shots, I autofocused using a single focus point, shot, went manual mode, set the lens focus at infinity, switched by to AF and re-shot the same image. The results were inconsistant. I tried the microfocus adjustment and really didn't see a whole lot of difference. Some images were just too soft for me and others dead-on sharp. I did find I obtained much better results by stopping down to at least f4. At f2.8 I could not get a crisp image at any point using either the LV or AF. Do I have a bum lens or camera?