<Tr> <Td> 300mm f / 2.8 L IS II USM </Td> <Td> Telephoto </Td> <Td> 300 </Td> <Td> 2.8 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> 300mm f / 4.0 L USM </Td> <Td> Telephoto </Td> <Td> 300 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> 300mm f / 4.0 L IS USM </Td> <Td> Telephoto </Td> <Td> 300 </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> 400mm f / 2.8 L USM </Td> <Td> Super-telephoto </Td> <Td> 400 </Td> <Td> 2.8 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr>

Why do some canon lenses have a red ring