In answer to your question, the 70-300mm becomes effectively a 105-400mm lens when used on a APS-c body such as your D7000. It is the result of a DX sensor being smaller than a FX sensor. Resulting in a 1.5 magnification factor for an FX lens use on a DX body. The DX lens being designed to cover the smaller sensor where the FX lens is designed to cover the larger sensor. The side benefit to using the FX klens on the DX body, in addition the magnification, is that you shooting closer to the center of the lens, thus losing distortions from the edges of the lens. Liked everyone's pictures, Happy shooting.