hi, I am in desperate need for one of the glass elements for my 400 2.8 is usm. A huge error has occurred which resulted in a chip in one of the elements and i fear no polishing will repair it. I have trawled the web and have contacted several out of service repair centers for any availability on spare parts with no luck so far. if anyone has an old lens as spares or repair or knows anyone that may have I would be hugely grateful!
It is the 5th mist rear element of the front group with the part number being yn2-1315 and it is the mk1 400 2.8 is version
https://www.ebay.co.uk/itm/Canon-EF...ded/274576983633?_trksid=p2485497.m4902.l9144 this one looks like a front ender so you might be able to salvage the lens you need.
Unfortunately they are different specs between the IS and the non IS version otherwise I’d snap that up!
