The trick behind smartphone camera focus

Modern smartphone cameras use voice coil motors (VCMs) to physically move glass lenses via electromagnetism — no gears or pulleys involved. When you tap to focus, an electrical current flows through a microscopic coil, generating a magnetic field that floats the lens forward or backward until the image sharpens. As phones add more cameras, the magnets from adjacent modules interfere with each other, forcing manufacturers like Apple and Samsung to develop complex software compensation algorithms to prevent cross-camera magnetic interference.