They come together at a point on the principal axis close principal axis An imaginary line which runs through the centre of a lens. called the principal focus F, (or focal point). The centre of ...

Principal focus of a convex lens: It is a point on the principal axis of the convex lens where all the light rays parallel to the principal axis converge after passing through the lens.

Fixed-focus lenses also remain popular for action cameras and 360 cameras. Related: Best new movies to stream on Netflix, Hulu, Prime Video, Max (HBO), and more ...

However, these lenses can't focus light of every color on the same point. It is a basic property of light that different colors—or frequencies—travel at different speeds in a lens.