Lens autofocus work using liveview / not viewfinder. Tried two different cameras (EFS 18-55mm Lens)

[ingallspw]

I have an issue with Auto Focusing on my EFS 18-55mm Lens.  It will autofocus using the LCD liveView screen but not the optical viewfinder.  I'll try not to blab so...

• Mechanically works perfectly (No odd noises, broken gears, etc)
• Tried two different camera bodies - Same result
• Reset all settings in cameras
• Updated firmware
• Cleaned lense, mirror, electrical contacts, etc.
• Image looks crystal clear using manual focus
• Again, autofocus works using view finder
• Other lenses work as expected on both camera bodies
• Image stabilizer on / off has no effect
• Cussing, crying, and other forms of a bad attitude have no effect either.

Any suggestions, ideas, fixes would be most appreciated!!!

[kvbarkley]

The only thing you did not try is another lens on that body. 

There appears to be a problem with the feedback during normal autofocus. I think the only thing you can do is send it to Canon.

[ingallspw]

Thanks for the feedback.

I guess I left a couple things out. I put multiple lenses on the same body. Basically I played musical chairs with the lenses and bodies. Other lenses work on thar body and the other but the problem lens does not work on either.

Also I did not mention that it mechanically tries to focus. Going through the entire range of motion but it blows by the focused image.

Also if I use manual focus, the focus indicator lights in the view finder give no feedback. No flashing red lights or beeping.

Has any one ever disassembled one of these leses? Could a ribbon cable popped loose?

[RobertTheFat]

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@ingallspw wrote:
Thanks for the feedback.

I guess I left a couple things out. I put multiple lenses on the same body. Basically I played musical chairs with the lenses and bodies. Other lenses work on thar body and the other but the problem lens does not work on either.

Also I did not mention that it mechanically tries to focus. Going through the entire range of motion but it blows by the focused image.

Also if I use manual focus, the focus indicator lights in the view finder give no feedback. No flashing red lights or beeping.

Has any one ever disassembled one of these leses? Could a ribbon cable popped loose?

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Or worn out, yes. But if this is to be your first attempt to repair a lens, you should start by assuming that you'll do more harm than good and write the lens off. That's not to say you shouldn't do it, especially if the lens isn't worth the cost of professional repair. It's just that you have to be realistic about your chances of success.

Also, could this be one of those cases where someone tried to manually focus a lens when it was in autofocus mode? With some of the cheaper lenses, that can jam the autofocus motor. Sometimes manually forcing the lens can unjam it. Canon has been known to post instructions for trying that.

[ebiggs1]

"Could a ribbon cable popped loose?"

The camera uses two different focusing schemes to AF in VF vs LV.  The lens does not. It has one way. If the lens does AF using one or the other it suggests the lens is OK. However, it looks like you have eliminated the camera so this seems to be the perfect time to upgrade to a nicer lens.

I would.  

[ingallspw]

Thank you all for your feed back!

Last night I was out taking photos with my son with the lens on manual focus.  It started making a motor noise seemingly for no reason. Then I took a photo and the camera said, "Lens communication Error". Rebooted. Seemed to work but then after a few photos I heard the motor noise again. Then a communication error. Then I noticed I could hear a rattle if you slightly shook the lens. So, now I know the lens is defiantly physically damaged but it I still wondered… why the communication error?

So going against all advice I took the lens apart. (I love to work on my own things.)

Inside all the gears looked great. as I was rotating the lens I was watching the rotating slide contacts in the lens. That is when I noticed a small piece of flat plastic. It was covering the rotating slide contact. Yep… that explains the communication error. So, I carefully grabbed it. The object is kind of shaped like a warped tear drop. On the flat sides, it has little extrusions, one on each side.

That’s when I noticed another identical part inside the view of the lens.

Ahhh… The aperture!

Booo!!!

Is that the sound of Taps playing?

[ingallspw]

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@ebiggs1 wrote:

"...this seems to be the perfect time to upgrade to a nicer lens."

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Any suggestions on a lense that won't break the bank and is compatible with a Rebel T6?

[RobertTheFat]

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@ingallspw wrote:

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@ebiggs1 wrote:

"...this seems to be the perfect time to upgrade to a nicer lens."

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Any suggestions on a lense that won't break the bank and is compatible with a Rebel T6?

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That depends on how profitable "the banik" is, but the correct lens for your purpose is the EF-S 17-55mm f/2.8 USM.

Unless, of course, you're planning an upgrade to a full-frame camera. In that case, the correct choice is the EF 24-105mm f/4L USM (I or II).

[Waddizzle]

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@ingallspw wrote:

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@ebiggs1 wrote:

"...this seems to be the perfect time to upgrade to a nicer lens."

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Any suggestions on a lense that won't break the bank and is compatible with a Rebel T6?

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If you have a small bank, then you might want to explore a used lens of the same type.  Visit KEH camera.  Use the selection filters to narrow the list of lens choices to Canon lenses, and EF-S Lens Mount.

Look for the “CANON 18-55MM F/3.5-5.6 IS STM BLACK EF-S MOUNT LENS FOR APS-C SENSOR DSLRS”.  This is the upgraded equivalent to the lens that you seem to have received in the camera kit with your camera.  Only buy an 18-55mm lens that has “STM” in the model number.

[ingallspw]

The bank is not very big so I just went and purchased an identical used lens.

Plus here is the fun part!!

After disassembling the lens and noticing the aperture was screwed up more than Channel 4 in a thunderstorm, I tried to put all the little fins back in place but one is warped and bent so just as an experiment, i just took out all the fins and put it all back together.

I was not sure what would happen but at this point... lets go for it right!?  Anyway, to my surprise, the lens works pretty well!  The autofocus works again and the communication error is gone.  I don't quite get the same depth of field but for now, its a decent emergency backup lens!  I've tried just searching to see if anyone was selling just the aperature's "little black thingy's" (leafs, blades, fins, shutters, or what ever they are called) but so far no luck. 

Thank you to all who replied and for all your suggestions!