Nikon SLR Cameras

Auto focus not working?

Guest
Guest

I just got in a Sigma 70-300mm APO DG, the auto focus isn't working? Is there something I'm not doing right? I have a Nikon D3100, isn't the sigma supposed to auto focus on the d3100? I like the focal length but it's kinda hard to stay focused on animals with manual focus, which is the only reason I got it.

Andrew
Andrew

The D3100 only autofocuses with lenses which have a built in motor (HSM suffix for Sigma) - if your Sigma doesn't have an, 'AF/MF,' switch on the side, it has no such motor.

Alan
Alan

On the lenses change mf to af

keerok
keerok

I'm guessing you didn't get the memo, right?

The D3100 will only autofocus with lenses that have a built-in autofocus motor. With Nikon lenses, you need to see the AF-S or AF-I spec. With Sigma, it's the HSM spec that tells if there's an internal motor present. DG only means it works for full-frame cameras.

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