70-200 f2.8 AF problem

[mish757]

Have a canon 70-200 f2.8 non IS lens that is having AF issues.  My other zoom lens (24-70 f2.8) is not having any issues paired with my 5D Mk III body, so pretty sure it is an issue with the 70-200.  The problem is with the AF on closer subjects (approx. within 25 ft) - on more distant subjects, the AF is tack sharp, but when I try to focus on a closer subject, the AF won't lock.  The motor continues to hunt for proper focus.  Tried cleaning the contacts, but still have the problem.  Anyone else have experience with this issue.  Thought I would ask you experts before shipping the lens off for repairs.

[mish757]

In reply to the last couple of posts (the lens is enroute to the repair facility so there isn't any new troubleshooting I can do):

- I didn't use the "Restore to Factory Settings" option, however I went methodically through every AF option in the camera menu and either changed or disabled the function to see if it had an effect.

- I was able to manually focus on subjects (even those within the 25 ft range), but I did not test the entire range of the manual focusing ring to see if there was any binding, etc.

- I have a standard UV filter on the lens that I never removed.  The UV filter, however, looked clean and undamaged to the naked eye.

Thanks to all that are contributing to this discussion.  You are a wealth of knowledge and information.

[mish757]

Update:  Notification from Canon repair facility:  "The USM in not functioning properly and needs replacement."

Parts, labor, and shipping:  $361.11

[TTMartin]

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@mish757 wrote:

Update:  Notification from Canon repair facility:  "The USM in not functioning properly and needs replacement."

Parts, labor, and shipping:  $361.11

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Thanks for the update. 

Well worth the repair, even in KEH's 'bargan' condition the lens sells for 3 times that.

[1hiphapa]

I also have a non-IS 70-200 that wouldn't focus on a person about 20' away during a sunny day yesterday. The focus would 'hunt' but never lock. Using a 7D MKII and my 24-105, 10-22, 50mm all work fine. Almost sent it into the Canon repair facility, then decided to clear all camera settings, put the lens on today and now it's working fine. For now anyway. Maybe it's a sign of malfunctions to come or maybe clearing everything was the fix, hmm...

[ebiggs1]

"Maybe it's a sign of malfunctions to come or maybe clearing everything was the fix, hmm..."

Well here is hoping for you.  But remember the camera doesm't focus.

[RobertTheFat]

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@1hiphapawrote:

I also have a non-IS 70-200 that wouldn't focus on a person about 20' away during a sunny day yesterday. The focus would 'hunt' but never lock. Using a 7D MKII and my 24-105, 10-22, 50mm all work fine. Almost sent it into the Canon repair facility, then decided to clear all camera settings, put the lens on today and now it's working fine. For now anyway. Maybe it's a sign of malfunctions to come or maybe clearing everything was the fix, hmm...

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Remember that a 70-200 has a switch to change the MFD. A subject at 20 feet may be close to the higher value, so it's conceivable that the switch was in the wrong position. Note Ernie's point that the problem was likely in the lens. Clearing the camera's settings may have been a red herring unless your test subject was at the same distance as the subject was when you had the problem.

[1hiphapa]

switch was not in the wrong position, it did the same thing in both 1.5 & 3...ended up manually focusing. 

[1hiphapa]

understood, just seems funny how after doing that the lens for now is working perfect in either 1.5 or 3. 

[Waddizzle]

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@1hiphapawrote:

understood, just seems funny how after doing that the lens for now is working perfect in either 1.5 or 3. 

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Sometimes a hair can find its’ way onto the image sensor.  I see no reason why a hair cannot find its’ way onto the lens mount connections.

[mish757]

Hi, I was the originator of this thread.  What you are describing sounds exactly like what I had happen with my lens.  It started out as an occasional problem that would go away for awhile.  Then one day the problem persisted.  If your problem comes back, I would guess it is probably the USM.  Good luck.