What Is A DO Lens?
The DO lettering seen on some Canon lenses stands for Diffractive Optics. You can spot a DO lens by the bright green ring around the front of the lens barrel, in a similar way to the red rings seen around Canon’s L-Series lenses. All lenses consists of a number of smaller glass elements within the lens barrel and Diffractive Optics is a technology that allows them to use considerably less optical elements in a lens design. They do this by bending the light much more with DO lens elements than they typically do with regular lenses. The result is a lens that is much smaller and lighter weight than its regularly designed counterpart would be. Due to the relatively high price of the technology, there are very few DO lenses available.