Last week I removed the front element from my Canon 28 - 135mm lens to remove a grain of sand from the lens. It was easy to remove the 4 screws, take of the top layer of glass and remove the grain.
I put the lens together again and I thought all was fine, wrong.
A week later I took the lens out for a shoot and the AF will not lock on, now the AF is constantly trying to focus and will not lock on to anything.
Have I broken the lens for good?