Simply put, when multicolor light (like white light) enters a new medium (like glass), the different colors bend at different angles. This spreading out of the colors is referred to as chromatic dispersion and means that the each color will reach focus at a slightly different point. Visibly, when you focus you will see the…

When multicolor light (like white light) enters a new medium (like glass), the different colors bend at different angles. This spreading out of the colors is referred to as chromatic dispersion and means that the each color will reach focus at a slightly different point making it impossible to focus your eyepiece on all of…