The location of your serial number varies between different Canon products. The serial number is a combination of numbers and/or letters, without spaces or special characters. Please ignore any numbers or letters that appear in brackets.
The serial number may be 5, 6, 7, 8, 10 or 12 digits long depending on the age and model of your lens.
It can be found in the following locations which are highlighted in the images below -
Please be aware that some lenses may also display a company code which could be mistaken for the serial number.
This company code can easily be identified as it will consist of letters and numbers.
An example of the company code and serial number is shown below -