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Encased Coin can be tough, getting copper toning correct can also be a pain, but there seems to be some pixelation issue going on (your last pics are much better).
it could be the lights you are using, either spectrum (most LEDs are around 3000K, where as 5000k-6000k is closer to natural daylight) or that the lights are too close.
try a non slabbed copper using natural daylight OR a 5000k (daylight) fluorescent bulb and post the results.
also, are you tapping the screen to set a focal point? I find that this will also help reset the "exposure"/saturation levels.
heres a few iPhone 4s shots - its just a matter of practice (unless the 5s has a different camera). far from pro quality but then again I don't take pictures for a living!


