that's the prob with the d40, only the new digital lens will work for autofocus.
you still can use the older lenses just that you have to manually focus.
im sure the shop who sold you shd've told you that only DX lenses work with the D40 and x
Just a little correction, not all the DX lenses are AF-S. The 10.5mm FE DX is a AF-D, IF lens. It required the screw drive to focus, so it can't AF on the D40/x.
DX is the format (dimension of the sensor/image size) and has nothing to do with AF. (All the current Nikon's DX lenses are AF-S though. Note that not all 3rd party lens maker for DX format can focus with your D40.)
Just a little correction, not all the DX lenses are AF-S. The 10.5mm FE DX is a AF-D, IF lens. It required the screw drive to focus, so it can't AF on the D40/x.
Actually if your D40 is still brand new, i advise you to see whether can you trade in for a D80 which is a much better DSLR, its like a baby version of D200 which accept all AF lenses.
Actually if your D40 is still brand new, i advise you to see whether can you trade in for a D80 which is a much better DSLR, its like a baby version of D200 which accept all AF lenses.