Coloured rings on canon lenses
Many EF lenses have a coloured ring around the front part of the barrel. This gives a good guide to the quality and performance of the lens.
At the top end of the range are lenses with a red ring. These are L-series optics, featuring aspherical elements and the use of special materials, such as ultra-dispersion (UD) glass and fluorite crystals. L-series lenses tend to have wide maximum apertures, which is another reason for their higher prices. It is said that the ‘L’ stands for luxury, but for a professional photographer they are essential. These are sturdy lenses with a solid construction designed for hard use.
Also at the top of the range are the green ring DO lenses. These use a diffractive optic to produce a lens that is significantly smaller and lighter than other lenses with a similar focal length. DO lenses are in the same class as L-series lenses as far as construction and performance are concerned.
ef40mm-f28stm4 net 15-85b
Current non-professional EF lenses have a silver ring at the front − they are often referred to as the consumer range. Older consumer lenses do not have an identifying ring. These lenses are good value for money and are often a sensible choice if you do not require giant enlargements from your images, and do not subject your lenses to heavy use. Some consumer lenses, such as the EF100mm f/2.8 Macro, approach L-series lenses in terms of performance.
You will see a dashed gold ring on some older lenses. This indicates the use of an ultrasonic motor (USM) for focusing. Silver ring lenses with a USM have the word ultrasonic in gold next to the ring.