http://www.nikonchat.com/nikkor-vr-18-200/

Nikkor help!?
Does the Sigma AF 18-200mm f/3.5-6.3 DC OS (Optical Stabilizer) Autofocus work of the project for D40x? Should I get the sigma 18-200 VR Nikkor to save $ 200? What is best lens for the $ $ $
I think the D40 can autofocus with the Sigma – I can guarantee not that. But basically, I would stick with the original Nikkor lenses for a better image and build quality. This is the extra money you are paying by – you get for what you pay.