How to fix your Canon 16 - 35mm L Series lens in under 3 minutes

You might find that over time, your Canon 16-35 mm L Series lens becomes loose at the top of the lens. I have been using mine for over 10 years and just noticed this problem.

At first i thought it would need to be sent into Canon to have it fixed, but if you've got 3 minutes to spare and a Philips #0 watchmakers screwdriver you can do it your self and save time and money.