Would this lens autofocus on my Nikon d5100?

This is my first DSLR and I'm still learning. I just realized that the camera will only autofocus with AF-S and AF-I lenses… Will this Sigma 28-200 3.5/5.6 Macro Compact-nkaf autofocus on my camera?

http://www.adorama.com/...81775.html

Added (1). I'm a poor college student so I'm trying to get the cheapest zoom lens (28-200mm) that I can possibly find. Any help or suggestions would be appreciated.

Added (2). Would not having AF really be that awful?

Added (3). Thank you, thank you, thank you! This is perfect! I really appreciate your help!

Probably not - Sigma lenses with motors are HSM.

You don't need a 28-200, just something longer than your existing 18-55mm - a 55-200 or 70-200 will serve you just as well, save you money, and won't hang around your neck like a bowling-ball.

This would be excellent for you;

http://www.adorama.com/...80052.html

Only you can judge whether or not you need autofocus - it may be a good idea to keep your options open.

The nomenclature nkaf seems to indicate Nikon Autofocus, which is what all the other Sigma lenses for Nikon are, that I'm aware of. Make sure of it when you are placing the order.

But, I have to wonder. Sigma does not list a 28-200mm lens in either its current or discontinued lenses. Is this a knockoff?

No it won't - it needs a focus motor in the lens to be able to autofocus on your camera, and for Sigma lenses, that means finding lenses marked with 'HSM'.

You're better off getting the 55-200mm or the 70-300mm to complement the 18-55m kit lens I assume you already have. Dunno what your budget is, but the Sigma 18-200mm is a good lens for the money

http://www.adorama.com/...02NKA.html

I appreciate that's a big jump in terms of cost, but welcome to the world of DSLRs!

The mere mention of autofocus is not enough. See the description if it mentions an internal motor. If none, it won't autofocus with your camera. In this digital age, no-AF is awful.

I grew up using SLRs that were manual focus only, and it became second-nature to manually focus them.

However, cameras in those days had a ground-glass focusing screen that really helped to manually focus the lens. Unfortunately, these days, DSLRs have no such focusing grid, and instead rely on a >. < type of indicator in the viewfinder that tells you when the lens is in focus.

You may find this hard to use…

Or maybe not.

Put your 18-55mm lens into manual focus mode, then go around for one day and try it. If it seems impossibly difficult, then you will certainly want an autofocus lens. One way or the other, you will know how much of an issue autofocus or lack thereof will be.