Dumb question

[rawfa]

Can anyone tell me if the sigma 15-30mm (http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3242) and the sigma 18-125mm (http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3342&navigator=6) are supposed to be able to autofocus with the D40? Because I know they both have the autofocus function but when I select the autofocus option ON the D40 it does not autofocus at all. Since I don't have any other autofocus lenses I have no idea if this could also be the D40 (I find it hard to believe, since it's a brand new camera).

[Jeff Anderson]

The D40 requires lenses that have their own internal focus motor ala Nikon AF-S series lenses. Not sure if any of the third parties have lenses with their own motors.

[capt chuck]

Did you turn both the camera AND the lens to AF? According to one of the reviews referenced in your links the AF switch on the sigma lenses may not be as obvious as on the nikor's... it says it is a push pull switch in the focusing ring itself.

[rawfa]

Yep, both the camera and the lenses were set to autofocus. I think it might be the motor thingy you've mentioned...

[Pettersen]

The D40 doesn't have an internal focus motor. In order to get autofocus to work with the D40, the lens need to have a focus motor. With nikon lenses, "AF-S" means that it has an internal motor. With sigma lenses, it's "HSM". In this case, only the 18-125mm will auto focus.

[rawfa]

Thanks, Mr.Eastwood! ;-)