Why Is Your Face Sometimes Upright and Sometimes Upside Down in a Spoon?

The inside of a stainless-steel spoon behaves approximately like a concave mirror. Light from each point on your face strikes the curved surface and changes direction according to the law of reflection. When your face is farther from the spoon than its focal point, the reflected rays converge in front of the spoon before reaching your eyes. Rays from different heights cross, producing an inverted real image.

Move the spoon slowly towards your face and the image grows, blurs, then turns upright once your face is inside the focal length. The reflected rays now reach your eyes before converging. Your visual system traces them backwards as though they came from behind the spoon, giving an upright, enlarged virtual image. The distinction between real and virtual is about whether the light actually converges at the image position, not whether one image is truthful and the other false.

Turn the spoon over and its outer surface acts roughly as a convex mirror. The reflected rays spread out, so the image is normally upright, virtual and smaller, while showing a wider field of view. A real spoon is not a perfect spherical mirror: its curvature varies, especially near the rim, so a face may stretch or distort, and the focal length depends on the spoon’s shape. The metal does not determine whether the image is upright or inverted; the curved surface’s handling of light does.

https://openstax.org/books/physics/pages/16-1-reflection