Hi.
My 100-400 has been unused for a while. I picked it up the other day and the focus is sticking towards the infinity end of the scale. This is the case with AF or manual.
When unmounted, I can reach in the back of the zoom and rack the mechanism manually with my finger but thats not a particularly helpful solution.
Anyone have any ideas or experience with this? Is there an easy solution or is it just back to Canon?
The danger signs with this lens are fine bits of black fibre coming out of the join between the tightening ring and the barrel and any change, especially looseness in the tightening ring. If these happen the end result if not repaired is seizure of the zoom.
Your problem sounds different, but I think I'd send it in, repairs on this lens get costly if something breaks inside.
Just came back from Canon (coz I only took it in the other day).
CPS replaced the USM assembly for ~$220 or so. Surprised at that one, and very happy.
It now focuses really well and is unbelievably sharp. Sharper than I ever remember it being.
