I use my EF100-400 on a Canon 10D. While in IS and auto focus mode, I was shooting a soccer match when the lens abruptly failed to focus, and I got an error message on the camera. I turned off the camera, removed the lens and remounted it. The lens would focus and the stabilizer would work, but after focusing and stabilizing the subject, the image in the viewfinder would abruptly shift to the left then pulsate.

My lens has worked perfectly since purchased on 2002. I can't find any information on troubleshooting or the problem I'm having. Can anyone out there help me or point me to a resource?


Sounds like a problem with the lens. To confirm, try using the lens on a different camera (perhaps you have a friend you whose camera you could borrow for a few minutes)? If it works fine on other camera, try using a different lens on your camera and see how things are. This should narrow down whether the problem is the lens or the camera.

Try turning off the image stabilization feature and see if the problem continues. It's possible the problem might only be with the IS.

If these things confirm it's a lens problem, you should send the lens to one of Canon's service centers and they can provide an estimate for repair.

  • +1 try turning IS on and off, try changing the modes, try manual focus, etc... Then give Canon customer support a call, describe what you are experiencing and they will walk you through a fix and/or have you send it in for repair. Canon Customer Support Center Hours: Monday-Friday 8:00 a.m. - 12:00 midnight. ET, Saturday 10:00 a.m. - 8:00 p.m., excluding holidays Phone: 1-800-OK-CANON (toll free) 1-800-652-2666 TDD: 1-866-251-3752 (toll free) Email: carecenter@cits.canon.com For additional support options: www.canontechsupport.com Apr 25 '11 at 11:56

The primary resource for problems like this is the lens manufacturer. They have people who are paid to troubleshoot this kind of problems, and repair centers to fix them.

The Canon USA support number is 1-800-OK-CANON, or visit their web site.


My first step would be to clean the lens and body contacts thoroughly

Then if that doesn't correct the problem try the lens on a friends Canon digital body to see if it behaves in a similar manner - if it does you've got a lens problem - if not your 10D has a problem.

If you do have lens or body problem the USA repair sites are:

Canon USA Inc. 15955 Alton Pkwy Irvine, CA 92718 tel: (949) 753-4237

Canon USA Inc. 210 Ward Avenue Suite 200 Honolulu, HI 96814 tel: (808) 522-5930

Canon USA Inc. 6325 Muirfield Drive Hanover Park, IL 60103 tel: (630) 582-8773

Canon USA Inc. 100 Jamesburg Rd Jamesburg, NJ 08831 tel: (732) 521-7007

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