Sigma 17-70 or Tamron 17-50???

I am adding a "walkaround" lens to my kit for mostly my wife's use on her XT... I want it to be a lens that she can destroy, and i don't care about it - she will probably wreck it in one way or another.

Can anyone tell me where the sigma's max aperture goes to f/4? Is it only f/2.8 at the 17mm length, or does it have 2.8 until maybe 50mm?

Does anyone have any real strong advice as to which is much better or worse than the other? At this point I am really just tempted to get the sigma, for the focal length, although if the tamron is very high quality/IQ... that is the one i'll get.


Any help is appreciated. FM doesn't have many reviews on either of these

I tested my Sigma 17-70, and here is the result:
17-20mm(about the middle point between 17 and 24mm mark) -- 2.8
21-24mm -- 3.2
25-35mm -- 3.5
36-55mm -- 4.0
56-70mm -- 4.5

Honestly the 2.8 on 17mm is only "usable", but wide open through 35-70mm is very nice. And don't forget the macro bonus. Use the manual mode at 70mm you can get things focused just 1cm away from front glass. I love this lens, highly recommend for walkaroud and kit lens alternative.

yeah I am with you this is a great lens

hard choice between these 2

CoolAir wrote in post #2497493
I tested my Sigma 17-70, and here is the result:
17-20mm(about the middle point between 17 and 24mm mark) -- 2.8
21-24mm -- 3.2
25-35mm -- 3.5
36-55mm -- 4.0
56-70mm -- 4.5

Honestly the 2.8 on 17mm is only "usable", but wide open through 35-70mm is very nice. And don't forget the macro bonus. Use the manual mode at 70mm you can get things focused just 1cm away from front glass. I love this lens, highly recommend for walkaroud and kit lens alternative.

Thanks alot for the scale of max apeertures! That helps alot in the decision process. I am gonna go to a local store and look at IQ, AF and build quality... I really need to know if anyone feels that one is far superior to the other...

...Any input?

If she shoots in lower light, the Tamron would be a better choice with its constant f/2.8 aperture.