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As many pixels as possible, but much more important is the light on the set. Careful not to shadows nor reflections, not to talk about contortions.
Light best 45° from the sides, if possible from 4 sides, the camera on a tripod centered 90° over the set to become an image. Use the remote timer to avoid any shaking of the camera. Make sure the set is sharp (distance control) and filling the frame as much as possible to get the maximum of pixels on the set. Crop the image afterward. Try to repeat the same for the rear side of the set, avoid taking the coins out…
Have fun
Globetrotter
Coin varieties in French:
https://monnaiesetvarietes.numista.com