17-70mm VS 24-70mm
 

I would like to know how much difference is between 17-70mm and 24-70mm, since they both have f2.8. But there is a big different in price!

Will they be serving the similar purpose?

please help

You might have to give us a clue and tell us the manufacturer. I'm guessing that the 17-70 is a crop-sensor lens (Nikon DX of Canon EF-S) where the 24-70 is full-frame.

Thanks GreenWing for responding to my question.

I am looking for a walkabout lens for my Nikon D5000, and trying to find out what is the main different between Sigma 17-70mm and Sigma 24-70mm, both at f2.8, but the later one is £100 dearer

I am also using Sigma 10-20mm, and nikkor 55-200mm.

To be more accurate, they are the Sigma 17-70mm f2.8-4.5 and Sigma 24-70mm f2.8 IF EX DG HSM.

There's a lot of difference. The 24-70 is a fixed f/2.8, the 17-70 is an f/2.8-4.5. Thats most of the cost. The 24-70 also has the HSM motor for faster and quiter AF, it's internally focusing so it doesn't rotate or extend when it focuses and it uses better quality glass.

You can look up what all the IF, EX etc stuff means on the Sigma website...

Well, the 24-70 is a full frame lens, as I suspected, and the 17-70 is what Sigma call DC, or we in the Nikon world call DX, so it doesn't cover the full 35mm frame. Also, the 24-70 is f/2.8 over the entire zoom range, but the 17-70 varies in maximum aperture from f/2.8 at 17mm to f/4.5 at 70mm, or probably less. These two factors mean that there's a lot more glass in the 24-70 - it weighs 715g, where the 17-70 is only 455g - and optical glass is expensive.

I think you're probably looking at the wrong 24-70 lens, though. Sigma have two models, the 24-70mm f/2.8 EX DG MACRO and the 24-70mm f/2.8 EX DG HSM. Of these, you want the newer, more expensive, and heavier HSM model, since the other will not autofocus on your D5000. I understand that it's a better lens than the older Macro model.

As a walk-around lens, the 17-70 would suit me better, as I often use wider than 24mm on my DX camera.

Edit: You may want to check the prices you've seen, too, as Warehouse Express has the 17-70 at £250 and the 24-70 at £450 (thats £200 more), with the 24-70 HSM coming in at £600.

Chris

Thankyou Chris n Greenwing

Both of you have given me a better understanding on these lenses. And have given me an idea what will be my next lens to upgrade.

Thanks again