A:AnswerYou can get close, but not as close as to be able to do any descent macro shots. For that you wold need a macro lens. If shooting full frame, this would be an nice all-around lens for almost anything but macro. If shooting cropped, this would work best as a portrait lens. Either way, a must have lens for any Nikon shooter. Just don't expect any macro abilities.
A:AnswerYes, you can use DX lenses on your D810. Be aware though, that the outside of the picture will cropped from FX size to DX size, but it works fine. The reason the image is cropped is that a DX lens will project a small image onto the sensor compared to an FX lens. The D810 automatically detects DX lenses and does the cropping for you. When you look through the viewfinder of the D810, you'll see an outline showing you where the cropping will happen.
