Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- User Rating: 
Summary for Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- Good lens but a bit bulky
Notes on Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- This is a great fast lens but in the end I opted for the Tamron 28-75/2.8 which, while not as wide, is just much easier to manage.
My two samples were also slightly flawed but perhaps I just got unlucky because otherwise the lens is very well regarded.
Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- User Rating: Summary for Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- Best glass for the money!
Notes on Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- I went through a second copy to find a good performer, but for the result I'm getting on my k10d, it was well worth the trouble. My first copy was bit soft at longer end and it wasn't what was expected from the review I was going by on the canon mount provided below. The exchange process was painless via amazon, as usual.
BTW, I've also tried Simga 18-50 f/2.8 EX DG and I've returned it in favor of Sigma 24-70 f/2.8 EX DG.
Once I got the second copy, it has been pleasure using the lens. I'll just point out the highlights:
Pros:
1) Excellent optical quality, no issues with CA or distortions at all focal length.
2) Image Quality at f/2.8 is very good and outstanding at stop down and peaks at f/5.6 in all focal length. If you're into sharp images this lens will deliver.
3) AF is relatively fast and not too loud.
4) 24-70 is still a great range for indoor use even with 1.5x crop factor.
Cons:
1) it's big and heavy.
2) related to size, better to use external flash due to shadow with built-in flash with lens fully extended/at the widest end.
All in all, this is the lens I use for indoors most of the time, however it performs even better with full sunlight at outdoors. If you don't mind the bulky size or the extra weight, this lens will be one of the best glass you can buy in the range of 24-70mm on a pentax mount. If I ever make a switch/or add canon/nikon body, then this is the lens I'll buy again for the other body.
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Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- User Rating: Summary for Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- The best general portrait zoom lens!
Notes on Sigma 24-70mm f/2.8 EX DG Macro Aspherical ...- I've used a number of lenses in the 28-70mm f2.8 class from Tokina, Tamron, Sigma, Pentax and Nikon. I can honestly say this is my favorite lens in that class.
I shoot with Pentax, Nikon, and Fuji cameras and the Sigma 24-70mm 2.8 DG lens is the only lens that I bought two of (one for my Nikon /Fuji cameras and one for my Pentax cameras).
I wouldn't call it the best lens in the world, but if I had to choose only one zoom lens to cover the 24-70mm focal lengths then this lens would be the one I choose.
