My recommendation:
  • use a tripod, level and make sure the camera is square with the wall and centered on the painting
  • use mirror lockup, and a cable release or self-timer to reduce vibration
  • ~40mm
  • f/8
  • ISO 100
  • distance somewhere between 10" (the minimum focus distance for the lens) and however far back you need to be to fill the frame



I recommend 40mm because zoom lenses (and especially consumer-level ones) usually perform best in the middle of the zoom range, not at the ends. A narrow aperture gives better performance with most lenses (the 18-55mm does poorly with the aperture wide open), but too narrow an aperture and you lose sharpness due to diffraction. For that lens and camera, f/8 is a good compromise. The lower the ISO the less noise, ISO 100 is the lowest your camera will go.


Make sure the paintings are well lit, with even lighting, off-angle to reduce reflections.


Good luck!