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.

[TCampbell]

On the side of the lens barrel, near the swtich which allows you to switch between auto-focus & manual focus, there is also a swtich which lets you set the focus range for the lens.  (e.g. 1.5 meters to infinity... or 3 meters to infinity.  The distance will vary based on which 70-200mm lens you own.

Check the switch to make sure you haven't set it to only focus at greater distances.  

[mish757]

Thanks for the reply.  AF problem occurs in both the 1.5m and 3m positions.  Not a matter of trying to focus on something too close - the AF problem happens anytime the subject is withing 25 ft or so.

[RobertTheFat]

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@mish757 wrote:

Thanks for the reply.  AF problem occurs in both the 1.5m and 3m positions.  Not a matter of trying to focus on something too close - the AF problem happens anytime the subject is withing 25 ft or so.

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Send it in for inspection then. You can't just let a 70-200 rust away. And unless you've actually worked for a Canon repair shop, you'd be crazy to open it up yourself.

Or are you just asking us to help you justify buying a new 70-200 IS II? If that's the case, then of course go for it!!

You have run the usual AFMA calibration tests, right?

[ebiggs1]

"... are you just asking us to help you justify buying a new 70-200 IS II?"

I'm all in for that idea !!!!!!!!!!! 

"You have run the usual AFMA calibration tests,..."

Nah, tain't that.  But you are right to be looking at the camera, IMHO, of course.

[TTMartin]

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@RobertTheFat wrote:

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@mish757 wrote:

Thanks for the reply.  AF problem occurs in both the 1.5m and 3m positions.  Not a matter of trying to focus on something too close - the AF problem happens anytime the subject is withing 25 ft or so.

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Send it in for inspection then. You can't just let a 70-200 rust away. Anu nuless you've actually worked for a Canon repair shop, you'd be crazy to open it up yourself.

Or are you just asking us to help you justify buying a new 70-200 IS II? If that's the case, then of course go for it!!

You have run the usual AFMA calibration tests, right?

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If it's the original EF 70-200 f/2.8 IS it is at least 7 years old, and could be over 15 years old. It's probably due an 11-Point Maintenance Service anyway. Send it in for inspection and cleaning.

[mish757]

Yep.  Looks like that's what I'm gonna do.  Thanks.

[ebiggs1]

"Tried cleaning the contacts, but still have the problem."

This almost to never helps or works. So, that is no surprise.

AF is achieved by the camera, not the lens.  The lens has no idea if it is in focus or not.  The camera tells it when it is.   I would look for a problem in the camera.  The best advise is to call Canon support.

[mish757]

Thanks, ebiggs.  If it is, like you say, a camera body issue, why doesn't the problem occur with my 24-70?  Not trying to be a PTA, just trying to learn.

[mish757]

Did a little troubleshooting since ebiggs suggested that it was a camera body vs lens issue.  Mounted my problematic 70-200 lens on my daughter's entry-level Rebel body, and had the exact same AF issue that I had when mounted on my 5D III body.  So it is definitely a lens problem and not a body problem.  And, no, I am NOT looking for justification for purchasing the new 70-200 II lens....