Why do objectives usually have a color ring inscribed on them?
With standard colors for most manufacturers, these rings make it easy to identify the magnification of the objective. A red ring means 4X or 5X. A yellow ring means 10X. A green ring means 20X. A blue ring means 40X, 50X or 60X. A white ring means 100X. Olympus also identifies phase objectives with a red ring nearer to the front lens of the objective, and identifies infinity-corrected phase objectives by making all inscriptions in the color green.
