Centre sharpness of these images show very small differences, we are virtually at the pixel-peeping level here. The Canon combination is possibly just that little better to be declared the "best", with the 200 VR almost neck and neck to it and the old-timer 50-300 a tiny bit behind. I'm not certain these minute differences survive to the web crops, though.
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The 300 mm (Canon) lens now operates close to the periphery (at the edge of the image) of its image circle and its performance declines accordingly, while both Nikkor lenses perform much better with far more image detail. Even the 50-300 lens, with its ancient optics harking back to 1977, can resolve fine detail such as single branches and spruce cones, all of which simply do not resolve on the Canon image.
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the Canon might have at least as good performance as D2X in the centre of the frame, but is let down by poorer performance towards the peripheral areas of the image.
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Thus, even though the bigger file size of the Canon would be considered to give a potential for larger prints, the lower sharpness outside the image centre conflicts with this. We might end up with the paradoxical situation in which both systems can deliver prints up to the same size in practice.