EFS 17-85 mm lens won't autofocus

[RemyMc]

Hi there,

My lens is about 7 years old and had an error recently - "connection problems", but that resolved- lots of fiddling, not sure what made the difference.  Now it won't autofocus - it seeks and seeks.  I've reset the defaults and taken the battery in and out and tried a different battery, but it all makes no difference.

Any ideas?  Could it be because the mirror was possibly moved - does that matter?

Thanks,

R

[ebiggs1]

"... the mirror was possibly moved - does that matter?"   

What, exatly does that mean?

[RemyMc]

Hi,

Basically there is a problem with my lens- EFS 17-85 mm (67 mm).  I am using it with my 40 D and it won't autofocus - it just keeps seeking and seeking.

(The mirror is a separate issue - probably a non-issue, so don't worry about it- sorry).

[ebiggs1]

Look at the conditions you're shooting in first.  Auto focus works by determining what is most prominent in the frame by analyzing how it contrasts with everything else. If the lighting conditions are too dark, then the camera will have trouble determining contrast.

"(The mirror is a separate issue - probably a non-issue, so don't worry about it- sorry)."

Oh, but it is - sorry!  Try a different lens. If it will not focus with it either, you likely need Canon service to look at it.

[RemyMc]

Hi there,

Yes, I have tried 2 other lenses and they both work.  The problem seems to be with the lens itself.  It will not focus under any condition.  I was hoping someone might have had the same problem and know if it is fixable or if it means the lens is toast.

Thanks.

[ebiggs1]

"... it means the lens is toast."

Unless you can clean the contacts on the lens and get it to work, yes.  Otherwise there is little that can be done cheaply.

You might call Canon service and ask. They may have just a bench fee for service on it.

[RemyMc]

Hi ebiggs1,

Thanks for your help.  I didn't realize Canon has a service line, so I'll try that and maybe a local camera shop just to see what they say.

Cheers,

Remy

[eugeneharvey]

Hi I have had 2, the first failed some years ago and was part of a 20D kit.  Liked the lense so got another one now that is having the same issues as posted.  The lens 'hunts' but won't focus.  All other lenses work with the body which is a 60D. I am of the belief it is a fault with the lens as this is the second to fail in the same manner.

[RemyMc]

Hi and thanks for the reply - I never did find the solution to this problem, I've just been working with other lenses.  I'm not sure if it is out of date software?? or what and am reluctant to mail it away for service.  I'm not sure what the final bill would be and yet it's doing no good sitting there.  Wierd that you've had 2 do the same - it must be a relatively common problem.  Is there a Canon help phone number by any chance?

[lly3988]

Does it make any difference when you switch the lens to AF and Manual modes ? Will the lens hunt in AF mode or simply showing no response when you half press the shutter. Since your other lenses are fine on your 40D, I would think that it is the problem with the lens.

I have opened up a few dead lenses of this exact model years ago and discovered that it was due to one of the followings :

1. the USM AF system was malfunctioning. User dropped the lens causing the part inside to come off and thus a loose retaining ring cannot provide enough pressure to allow the AF (USM motor) to rotate and AF.

2. a loose/broken flex cable causing communication problem. ( some DIYers opened up the lens and broke the cable and in another case, the guy did not insert the cable properly into the connector) The camera cannot command the lens to AF.

There are of course other possible reasons :

3. a malfunctioning PCB board.

4. a broken AF/MF switch.

5. and other causes which I haven't come across.

My suggestion is to give a call to Canon repair center in your area and ask for assistance. This is a very old lens with a lot of production. After these years, I think the Canon people should have a lot of information about the problem of this lens.

It costs just less than $200(shipping and tax included)  to get it repaired. Worth it or not ? It's up to you to decide. Ask for a quote and if you think it is not the best choice, think about a replacement.