EF100-400mm L IS II USM suddenly stopped focussing

[MikeMazet]

I replaced my EF100-400mm first series lens with 2nd series a couple of years ago. I noticed over the last few weeks that focussing had become problematic with the lens failing to focus on the occasional subject (mostly birds among thickets of tangled branches). This seemed intermittent and I was hoping it was the branches that were causing the issue. But, suddenly, overnight the lens stopped focussing altogether, and that's when pointing at clearly defined, uncluttered subjects. I am an experienced photographer and know this isn't down to wrong settings etc. But what can be the cause? Are the motors on these lenses likely to fail after 2 years? The motor still drives the focussing but not every time, and it never achieves focus. After a couple of whirrs it gives up. If it's the motor, is it worth replacing? Anyone know the cost? (I'm in France, so a € price would help.)

[Waddizzle]

“ I have 5D MkII and 7D MkII bodies and the 100-400 no longer works with either body. It is usually left mounted on the 7D. “

Well that pretty much sums it up right there alone.  There seems to be an issue with the lens.  It needs to be sent in for an inspection and a likely repair.

[Waddizzle]

BTW, if you switch it to Intelligent Auto Mode, Green[A+] mode, and it still does not want to focus on either body then there is definitely an issue with the lens.

[ebiggs1]

" It needs to be sent in for an inspection and a likely repair."

Not so fast Mike, yes, I agree, yes, it is probably the lens and, yes, it is worth servicing. However lets do a simple test first. You have found out that cleaning the contacts never, I used to say rarely but never seems a more appropriate word, helps. But a full reset of either or both of your fine cameras just might. Do a Clear all settings and Clear all custom settings. The latter is very important so don't pass it by.

Now set either one to P mode. One shot never Ai-servo and make positive the lens switch is in AF. ISO 200 and daylight. Now on a bight sunny day go outside and try to shoot various subjects. Make sure they are high contrast and have vertical lines in them. Like a fence or buildings, light poles anything just varied subjects. If it doesn't work you can be pretty assured it is faulty and needs service.

Mike anything made by the hand of man can and will eventually fail. Some sooner than others and some sooner than they should. Canon may not be the cheapest repair but they will go through the entire lens and make sure it is up to spec. And you will get a warranty of their work and parts.

[MikeMazet]

Thanks EB. I’ll try your suggestions in day light tomorrow.

[Waddizzle]

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@MikeMazet wrote:

Thanks EB. I’ll try your suggestions in day light tomorrow.

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Testing the lens in Green[A+] mode has the net result as resetting the camera.  If the lens does not focus, then it needs to be checked out and probably repaired.

[Anonymous]

Have you checked the setting in the AF menu for the setting of Lens drive when AF impossible and make sure it is set to ON. This sometimes helps when a long zoom lens has issues focusing.

[MikeMazet]

Not sure what Green(A+) mode means but if it is a camera setting maybe it's not available on MkII models of 5D & 7D. Yes, I did check the 'lens drive when AF impossible' setting, but same negative result. And tried EB's suggestions of full camera reset, P @ 200ISO, sunny morning here, sharp high contrast lines of rooftops/walls. Lens still won't focus.  No option left but to give the lens to Canon. Great community, guys! Thanks for all your help... 

[Waddizzle]

Green [A+] mode?  Look at the shooting mode dial on top of the camera.

[EDIT] Let us know how you make it with the lens repair.

[MikeMazet]

Oh that! I've never used it before, but still can't achieve focus...

[ebiggs1]

"Testing the lens in Green[A+] mode has the net result as resetting the camera."

I don't like the "Green Square" always telling people with this level of camera to forget it even exists. If you want a P&S buy a PowerShot. But if you are going to buy a semi-pro camera you should be beyond the Green Square! Besides I prefer to have the camera set back to a completely known zero in every respect.

Sorry it didn't work but now you know for sure. Call Canon 1 (800) 652-2666