I first noticed this with my Olympus M.Zuiko 12-40mm f/2.8 Pro. I’d knocked it off a table and, although it didn’t fall very far, I gave it a little shake to check nothing had come loose and there was a noticeable ‘clonk’ from inside. Not good!
I didn’t have another lens with me so I had to put it back on the camera to check it out and hope for the best. The shots were fine, which seemed weird, but then I noticed that with the lens on the camera and the camera powered up, the clonk was gone.
