I misused the term "Field of View," when I meant the same subject area. If you were copying a slide with the same lens, the DX camera would use less magnification and be further from the slide. If you print or display that image at the same size, the DX camera would require more magnification. 1:1 is always the same magnification, but you would get less of the subject on a DX sensor. It is possible that an FX lens on a DX camera would incur flare due to the extra light bouncing around inside the camera. In practice, it probably doesn't matter. I used DX sensors for years, but always with FX (film, actually) lenses without any unusual flare or internal reflection problems. If you think about it, only about 50% of the image circle is used with an FX sensor, with plenty of opportunity for internal reflections.