Question about Camera Lenses

1 Answer

Manual Focussing failure with Canon EF 100-400mm SLR zoom lens

I have a Canon SLR lens which I use with an EOS 20D body. I have had the lens for a year and foud the other day that the manual focus funcion no longer works, the focussing ring just turns around on the lens barrel and makes no difference to the focus at all. The auto-focus function thankfully still operates, so I can still use the lens, but there are situations where manual focus is necessary. Is there anything I can do to restore the manual focus or is this a job for the technicians?

Posted by on

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 667 Answers
Re: Manual Focussing failure with Canon EF 100-400mm SLR...

I doubt if there is anything you can do yourself. The manual focus may have debris under the ring or is in need of parts. I would leave this one to a tech.

Posted on Jan 23, 2008

Add Your Answer

0 characters

Uploading: 0%


Complete. Click "Add" to insert your video. Add


3 Points

Related Questions:

1 Answer

Hi- purchased the Extender EF 2X II; it seems fine with my fixed focus 300mm, but the auto-focus doesn't operate with my 70-200mm EF IS USM zoom, in any mode. Any suggestions? Thanks G

You haven't stated which body you have but the AF will not work with the extender if the effective lens aperture is too low (remember that a 2x extender doubles the focal length but halves the effective aperture).

Canon's own website states: "Autofocusing does not operate if the effective maximum aperture is greater than f/5.6 (greater than f/8 on the EOS 1V and EOS 3)."

Aug 01, 2010 | Canon Extender EF 2x II Lens Converter

1 Answer

My lens is locked and i cannot zoom

I had the same problem with the same lens. Over a few months it got lose, eventually getting so sloppy that it dropped if my 40D was held down. 10 days ago it jammed and the zoom was locked. I sent it to Canon and received it back in a week and it is now like new. Please don't try and fix it leave it to the experts at Canon. Not sure what the cost was as mine was still just under warranty
I think that this is a common problem with this lens and beleive that something in the lense works loose and eventually drops into the mechanism.

Jun 28, 2010 | Canon EF-S 17-85mm f/4-5.6 IS USM for EOS...

1 Answer

I just purchased a Sigma 2.8 f=28mm for canon but I don't know if it will fit my Canon EOS 500 N (same as Rebel G) 35mm SLR film camera. Can you help with this question.

Canon EOS 500N has an EF lens mount, so all lenses with Canon EF mount will fit. All lenses with MF and EF-S won't fit. If you purchased Sigma 28-70mm f/2.8 EX, then it have EF mount and will fit EOS 500N.

Jun 06, 2010 | Sigma Zoom Wide Angle-Telephoto 28-70mm...

1 Answer

00 on the F info (aperture shows 00)

I'll assume the lens is an AF lens? Most of the new Canon bodies require AF contacts. If there isn't the right contacts, it won't work. There are suppose to be AF body mounts that will tell the body that there is an AF lens, then use the old lens in Auto mode.
If it's an AF lens, the internal electronics are toast. You could send it out, but they'll charge you a "look at" fee. That could run into many bucks. Give Canon a call.

Jul 26, 2009 | Canon EF-S 17-55 f/2.8 IS USM Lens

1 Answer

New Camera

Get the Canon EF 70-300mm IS USM about $500 and EFS 17-85mm IS USM about $300. The 75-300 all of them I would not use them 4 a body cap. Camera is fine or step up to XSI.

Jun 10, 2009 | Canon Zoom Telephoto EF 75-300mm f/4.0-5.6...

1 Answer

Cant adjust below f/5.6 on a eos 40d

You are correct in thinking that it should be possible to set the aperture wider than f/5.6 at the wide end of the zoom range.  My best guess is that the lens is defective.  I'd suggest returning it for a replacement.

Dec 21, 2008 | Canon EF-S 17-85MM F/4-5.6 IS USM Lens

1 Answer

Autofocus function will not work on Canon 17 40mm 1.4 EF lens

Since the problem is limited to this lens, I highly doubt that you would have to replace the cameras AF sensors.
Since you only have the problem with this lens, I am afraid that you will have to get the lens repaired. Is the lens also 3 years old? Did you get it with MACK extended warranty?
Sometimes, Canon do these kinds of repairs for free, if they discover that there was some manufacturing error that caused it to fail. So be sure that you get it to a certified canon workshop. 
I hope this helps, 

Nov 24, 2008 | Canon 35mm f/1.4L EF USM Autofocus Lens

1 Answer

Transfering my ef lenses to digital cameras

Hi Marc! Almost all EF lenses, including the two you listed will work on the Canon Digital SLRs. On the Digital SLR they will have 1.5x the magnification that they would have on a 35mm camera. Your 28-90 will be like a 42-135mm and the 75-300 would be like a 112-450mm. This is because the image sensor on the Digital SLR is smaller than a 35mm negative.


Aug 03, 2008 | Canon Camera Lenses

Not finding what you are looking for?
Camera Lenses Logo

Related Topics:

922 people viewed this question

Ask a Question

Usually answered in minutes!

Top Camera Lenses Experts


Level 3 Expert

93922 Answers


Level 3 Expert

3283 Answers

Bart Pulverman

Level 2 Expert

354 Answers

Are you a Camera Lens Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides