Canon 28-105 f/3.5....should I trade for Sigma 24.70 f/2.8?

I currently have the canon 28-105 f/3.5 lens....and like it a lot....however...I just got a call from a friend wanting to sell me his sigma 24-70 f/2.8. Is this lens worth me replacing my 28-105? I can sell my canon lens and the difference in cost from me selling and purchasing the sigma is only an extra $100 out of my pocket? I know the sigma gets good reviews, but i've also seen good review on the canon lens. I think i know the answer, but I just need the little push....

Thanks.

Ok, I'll give you the push you need - KEEP THE 28-105!

How would you benefit from selling a fantastic lens and paying $100 on top of it to get the Sigma? Will it be sharper? No. Does it have an equal focal range? No. Will you get a slight improvement in low-light? Yes.

Ok, my math, two for the Canon vs. one for the Sigma.

Again, keep the Canon and your $100. A trade up is one thing and, although I've never owned that particular Sigma, I don't see loosing the 28-105 plus the added money as a trade up.

I gotta agree with HRC, I'd keep the 28-105 and for your next upgrade look at moving up to a nice ultrawide or telephoto depending on how you shoot. That 28-105 is far to versatile to let go, and if it ain't broken don't fix it!

thanks guys....just wanted to make sure. I'm saving for the 70-200L, so I guess I'll add the $100 to it.

Good idea!

If his lens is a good copy, then I would say go for it even if you have to pay the $100.