what do the colored rings on canon lenses mean
Canon L lens 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,[1] 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/2.8L) 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.