<P> Larger sized L - lenses , such as the 70 -- 200 mm , 100 -- 400 mm zooms , and longer focal length primes ( 300 mm+ ) , usually have an off - white barrel to reduce heat absorption under the sun that may otherwise affect the performance of the lens , as well as to identify Canon 's lenses ( for example at sporting events ) , though these can be confused with Sony A and Pentax K - mount lenses which are also offered in ( pure ) white . However , shorter focal length L - lenses can be black ( such as the Canon EF 24 -- 70 mm f / 2.8 L ) and all L - lens primes under 200 mm are black . L - lenses can be identified by the distinctive red ring on the lens barrel . The off - white colour of the lens barrel is not exclusive to L lenses , since the Canon 400mm f / 4 DO non-L lens is off - white with a green ring . </P>
what do the colored rings on canon lenses mean
to reduce heat absorption under the sun that may otherwise affect the performance of the lens to identify Canon 's lenses