Just noticed the manual focus ring on my EF100-400 grinds at the 100 setting even though the overall AF seems to still work just fine, Canon estimated the repair cost will be over cdn$500.
The interesting part is that this is the second time this "focusing ring unit" has failed, I've had this lens for 5 years now, the first time it failed was at two years, it was fixed for free under good will, now 3 years later it has failed again. I very vaguely remember something in this EOS user group forum that someone mentioned the manual focus mechanism is tied to the friction ring that locks the lens barrel in place so the zoom setting doesn't change, I regularly tighten this ring (but not excessively) to keep the lens in the shortest length while the lens/camera is hanging over my shoulder, I wonder if the tightening of the friction ring causes premature wear of the focusing ring unit?? I will do a search of the archive to see what I can find. So, in the mean time, may I suggest you EF100-400 users to minimize your use of the friction ring, I know I will probably never use the friction lock again after paying for this repair........ Regards, Ken * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
