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New Contributor
Posts: 2
Registered: ‎12-17-2018

Canon Lens only autofocuses during full zoom or no zoom

Hello,

 

I have a canon EFS 18-55mm lens that I've been using for 5-6 years. The lens is in great condition cosmetically, but recently started having a peculiar problem. I usually use the lens in autofocus mode with the camera in auto as well. Recently, the lens will not autofocus unless I have it zoomed completely in or zoomed completely out. That is, if I zoomed to something in the middle of its range, then it will not autofocus and thus will not allow me to take a picture.

 

I have opened the lens up and verified that the gears are all intact. The lens does move slightly to autofocus, so that tells me that the motor must be in working order. Does anyone have any ideas as to what may be causing the issue? 

 

Much thanks,

 

Storm

Respected Contributor
Posts: 1,083
Registered: ‎02-06-2013

Re: Canon Lens only autofocuses during full zoom or no zoom


@arrivingstorm wrote:

 

I have a canon EFS 18-55mm lens that I've been using for 5-6 years. The lens is in great condition cosmetically, but recently started having a peculiar problem. I usually use the lens in autofocus mode with the camera in auto as well. Recently, the lens will not autofocus unless I have it zoomed completely in or zoomed completely out. That is, if I zoomed to something in the middle of its range, then it will not autofocus and thus will not allow me to take a picture.

 

I have opened the lens up and verified that the gears are all intact. The lens does move slightly to autofocus, so that tells me that the motor must be in working order. Does anyone have any ideas as to what may be causing the issue? 

 

 


The cause could be a number of things but I wouldn't be surprised that one of the flex cables inside the lens broke in such a way that prevents a certain zoom range.

 

I'm not sure if the hassle and expense to have it fixed are worth it for this particular lens.  You can search youtube for EFS 18-55mm lens flex cable...there are videos that will tell you how to check and repair by replacing the cable.  The cable can be bought via ebay for a very reasonable price.

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Diverhank's photos on Flickr
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Posts: 10,651
Registered: ‎12-07-2012

Re: Canon Lens only autofocuses during full zoom or no zoom

I don't know if this will work since you took the lens apart. I never recommend folks do that if you are not a Canon tech.

However at this point it can't hurt to try this.

 

Take the lens off of your camera.

Put the lens in MF mode.

Twist the FOCUS ring (the tip of the lens) all the way to one side (extend it). You may hear a click noise or two, this is good, but don't FORCE the lens.

Twist the FOCUS ring all the way to the opposite side (retract it). Again, you may hear a couple of clicking noises. What we hope is happening is the focusing motor being put back into its proper place.

Put the lens back on the camera.

Put the lens in AF mode.

Turn the camera on.

Put the camera in AUTO or P mode.

Take a test photo.

EOS 1DX and 1D Mk IV, along with less and less other stuff.
New Contributor
Posts: 2
Registered: ‎12-17-2018

Re: Canon Lens only autofocuses during full zoom or no zoom

Thanks for the idea! I looked up some videos on this and I'm not 100% sure if this is my issue, but maybe its possible. But, before I go through and take it out, do you know if there is any way to confirm that the flex cable is malfunctioning? Seems to me like any break or fault in the cable would be impossible to diagnose visually. 

Respected Contributor
Posts: 1,083
Registered: ‎02-06-2013

Re: Canon Lens only autofocuses during full zoom or no zoom


@arrivingstorm wrote:

Thanks for the idea! I looked up some videos on this and I'm not 100% sure if this is my issue, but maybe its possible. But, before I go through and take it out, do you know if there is any way to confirm that the flex cable is malfunctioning? Seems to me like any break or fault in the cable would be impossible to diagnose visually. 


I agree with you that it's not possible to diagnose visually. I don't know of a method for detection - sorry.  It might be worthwhile to try the procedure that ebiggs posted.  That fixes another cause for this kind of lens to go wrong.

================================================
Diverhank's photos on Flickr
VIP
Posts: 10,651
Registered: ‎12-07-2012

Re: Canon Lens only autofocuses during full zoom or no zoom

I have no certain reason but IMHO, I would highly doubt any flex cable is the cause. I think that would be a go or no-go situation. My thoughts?  Focus does not depend on where the zoom is.

EOS 1DX and 1D Mk IV, along with less and less other stuff.
Honored Contributor
Posts: 5,490
Registered: ‎11-13-2012

Re: Canon Lens only autofocuses during full zoom or no zoom

https://community.usa.canon.com/t5/Lenses/canon-EF-S-18-55-random-auto-focus-problem/td-p/146729

John Hoffman
Conway, NH

1D X, Rebel T5i, Many lenses, Pixma PRO-100, MX472, LRCC Classic
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Posts: 10,651
Registered: ‎12-07-2012

Re: Canon Lens only autofocuses during full zoom or no zoom

Yeah, I remember that thread but it does not change my thoughts one tiny bit, " I would highly doubt any flex cable is the cause."  I did not subscribe it was the cause in that thread either. The cable would have to be focal length or specific zoom range aware.  It is not.

EOS 1DX and 1D Mk IV, along with less and less other stuff.
Honored Contributor
Posts: 5,490
Registered: ‎11-13-2012

Re: Canon Lens only autofocuses during full zoom or no zoom

The cable doesn’t have to be “focal length aware”. But, when the lens zooms the cable flexes and certain cable positions can make/loose connections if the cable has a break.
John Hoffman
Conway, NH

1D X, Rebel T5i, Many lenses, Pixma PRO-100, MX472, LRCC Classic
VIP
Posts: 10,651
Registered: ‎12-07-2012

Re: Canon Lens only autofocuses during full zoom or no zoom

[ Edited ]

"...when the lens zooms the cable flexes and certain cable positions ..."

 

OK, whatever, but that, means the cable would have to reattach or reconnect broken wires when it got all the way stretched out or all the way contracted.  Plus doing so many times!  I am still not going for it.  

EOS 1DX and 1D Mk IV, along with less and less other stuff.
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