DX mode is just a crop. Literally all it does is to fail to save the pixels outside the DX crop area. There's no magnification applied. There is no impact on the focus, there's no impact on the image otherwise. The only way the image turns out differently is that the metering is done only on the DX area, for obvious reasons: that's all of the image. Aside from the metering aspects, you'll get the same image if you shoot the DX crop and print it, as if you shoot the FX image, print that and then take a razor blade and cut the DX area out of the FX print.
_____ Brian... a bicoastal Nikonian and Team Member
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