http://www.nikonchat.com/nikon-d40-lenses-compatibility/
What I can use lenses nikon d40 digital camera?
Hello, I get a stronger purpose for my camera. "I can buy any digital lens for it or only support the nikon?. If you can only use a limited number then there is a place I can check the compatibility? Thanks
Nikkor and Sigma are usually the brand of lenses with the correct assembly, with the Nikon Nikkor brand. If you want to continue using the automatic focus function, then you have to find the Nikon lens mount with AF-S or AF-I, which shall include in its description. If you are good with manual focus then you can also use a regular F-mount. Any third party lenses should note the compatibility (at least online) to help with your decision. Hope this helped. I put a link where I got most of my information and it actually has useful guide to finding more lenses. In addition, a link to Amazon.com after Search "lenses D40"