Will my Nikon D3100 autofocus if I buy a Sigma lens?

So, I have a Nikon D3100 and I want to buy a Sigma - 70-300mm Macro DL DG Lens for Nikon AF-D. I know that my Nikon does not have an autofocus motor built in, but the Sigma lens does. My question is, will this lens autofocus on my cam?

What you need is a built-in autofocus motor, and since this Sigma lens has it, you're D3100 will work perfectly with it.

For a complete list of lenses that autofocus with your D3100, look at this webpage.
http://en.wikipedia.org/...cus_motors

Are you sure about the focus motor? Sigma has a special designation for the lenses with a focus motor built in, HSM. This is the same as Nikon AF-S or Canon USM or Sony SSM.

I don't think the 70-300 is an HSM lens.AF-D is not the same thing as AF-S! A Nikon "D" lens means the lens transmits distance information to the camera for flash exposure calculation, it actually has nothing to do with the focusing system.

If this lens has HSM in the name, it will work with your crippled camera. If not, then it won't.