Understanding Resolution - Do You Need More Pixels?
… What that means is that after 10M, the perceivable resolution increase one receives from every 1M increase of megapixels is less than .5M, and after 20M, the perceived resolution increase for every 1M is less than .1M. As a practical matter, after 20M, the more megapixels simply become “the Emperor’s new cloth” which really is not there to be seen.
… Overall, even with a full frame, going from 10M to 20M has less than 50% increase in perceivable resolved pixels even with the best lenses. You’re certainly not doubling the resolved pixels there. Of course, even an increase of 50% can be important for some people who (1) actually need a greater resolution; and (2) actually have possession to the top lenses and use them. On the other hand, with the same technology, going from 10M to 20M will lose at least one full stop of the ISO performance.
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