topic Re: 70-200 f2.8 AF problem in EF & RF Lenses

70-200 f2.8 AF problem

mish757 — Mon, 24 Jul 2017 16:16:13 GMT

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.

Re: 70-200 f2.8 AF problem

TCampbell — Mon, 24 Jul 2017 17:52:16 GMT

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.

Re: 70-200 f2.8 AF problem

mish757 — Mon, 24 Jul 2017 18:30:08 GMT

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.

Re: 70-200 f2.8 AF problem

ebiggs1 — Mon, 24 Jul 2017 21:00:03 GMT

"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.

Re: 70-200 f2.8 AF problem

RobertTheFat — Mon, 24 Jul 2017 21:40:29 GMT

@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.

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?

Re: 70-200 f2.8 AF problem

ebiggs1 — Mon, 24 Jul 2017 21:05:57 GMT

"... 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.

Re: 70-200 f2.8 AF problem

mish757 — Mon, 24 Jul 2017 21:35:38 GMT

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.

Re: 70-200 f2.8 AF problem

TTMartin — Mon, 24 Jul 2017 21:41:24 GMT

@RobertTheFat wrote:
@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.
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?

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.

Re: 70-200 f2.8 AF problem

mish757 — Mon, 24 Jul 2017 21:45:56 GMT

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....

Re: 70-200 f2.8 AF problem

mish757 — Mon, 24 Jul 2017 21:46:46 GMT

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

Re: 70-200 f2.8 AF problem

ebiggs1 — Tue, 25 Jul 2017 14:09:01 GMT

Still think it might be the camera.

Whenever a camera seems to be doing something strange (or not doing what it should) it's worth a try to use the 'restore all settings to factory' option. The lens doesn't know when it is in focus. The camera does. You may have a C.Function set incorrectly.

Besides that it could be you. The scene you are trying to shoot. No contrast, too dark, too close, etc, for instance.

Re: 70-200 f2.8 AF problem

RobertTheFat — Tue, 25 Jul 2017 16:30:15 GMT

@ebiggs1 wrote:
Still think it might be the camera.
Whenever a camera seems to be doing something strange (or not doing what it should) it's worth a try to use the 'restore all settings to factory' option. The lens doesn't know when it is in focus. The camera does. You may have a C.Function set incorrectly.

Besides that it could be you. The scene you are trying to shoot. No contrast, too dark, too close, etc, for instance.

And I still think it might be cured with AFMA (assuming that the camera isn't a Rebel). The nice thing about AFMA is that it doesn't matter whether the problem is in the camera or the lens. It treats the symptom, not the disease.

Re: 70-200 f2.8 AF problem

kvbarkley — Tue, 25 Jul 2017 16:55:38 GMT

Except the problem is not that the focus is off, it just can't focus, it hunts.

It looks to me that for some reason there is a lot of play in the AF connection to the focusing elements at 25 ft distances.

Re: 70-200 f2.8 AF problem

mish757 — Tue, 25 Jul 2017 17:07:39 GMT

You guys have way more knowledge about this stuff than I do. What is AFMA? And when you say "a lot of play in the AF connection to the focusing elements", is that something in the lens itself? Moot points since the lens is in the mail to the Canon repair facility...just curious.

Re: 70-200 f2.8 AF problem

TTMartin — Tue, 25 Jul 2017 17:18:58 GMT

@mish757 wrote:
You guys have way more knowledge about this stuff than I do. What is AFMA? And when you say "a lot of play in the AF connection to the focusing elements", is that something in the lens itself? Moot points since the lens is in the mail to the Canon repair facility...just curious.

AFMA is used when a lens is focusing, but, either front or back focusing instead of accurately focusing. Since your lens was having difficulty focusing at all, I doubt AFMA would have fixed your issue.

Re: 70-200 f2.8 AF problem

mish757 — Tue, 25 Jul 2017 17:28:12 GMT

Thanks, TT. I think you're right. It's not that it was focusing and the image was coming out blurry, it wouldn't focus at all on the closer subjects. When it focussed on a more distant subject, the image was sharp.

Re: 70-200 f2.8 AF problem

RobertTheFat — Tue, 25 Jul 2017 19:42:55 GMT

@mish757 wrote:
You guys have way more knowledge about this stuff than I do. What is AFMA? And when you say "a lot of play in the AF connection to the focusing elements", is that something in the lens itself? Moot points since the lens is in the mail to the Canon repair facility...just curious.

We're just thinking out loud. You're doing what we'd probably do if we were in your shoes.

AFMA is "autofocus microadjustment". It's a method of calibrating the accuracy of the AF mechanism. Most higher-level Canon cameras have it. The Rebels don't. If your camera has it, it's described in the instruction manual.

Re: 70-200 f2.8 AF problem

ebiggs1 — Tue, 25 Jul 2017 19:46:01 GMT

Robert from B Town, it ain't AFMA. It might be a C. Func., though.

Re: 70-200 f2.8 AF problem

TCampbell — Tue, 25 Jul 2017 19:52:12 GMT

It sounds like your lens needs service.

If you focus the lens manually, is the focus able to move freely from closest focus to infinity?

Note that "L" series lenses with USM focus have a clutch which allows the focus mechanism to slip against the rotation of the focus ring on the lens barrel. So you'd probably want to look through the lens or watch the focus distance scale in the window move as you rotate the focus ring.

You're looking to see if it has the full range of focus range without sticking or jamming.

Re: 70-200 f2.8 AF problem

Waddizzle — Tue, 25 Jul 2017 23:39:56 GMT

Two questions:

!. Are you able to focus the lens manually at those ranges?

2. If you have a filter on your lens, remove it. That's one less question mark in the problem.