Af successful in only certain conditions

[filionugo]

Hi! I am a novice at photography. I bought a used rebel t3i with the stock lens on it (18-55). I believe it's the stm version. It was working fine but know I have a problem. The autofocus only works when it has to turn counterclockwise. If it has to turn clockwise it will still turn counterclockwise. I'm trying to figure out what's the issue.

Thanks!

[RobertTheFat · Accepted solution]

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@filionugo wrote:
Hi! I am a novice at photography. I bought a used rebel t3i with the stock lens on it (18-55). I believe it's the stm version. It was working fine but know I have a problem. The autofocus only works when it has to turn counterclockwise. If it has to turn clockwise it will still turn counterclockwise. I'm trying to figure out what's the issue.

Thanks!

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If it's the STM version, it should say so on the lens. If it isn't, it may have been damaged by someone trying to focus it manually while it was in AF mode. Such damage is sometimes reversible, and the (rather brutal) technique for doing so has been described two or three times in this forum. It sounds as though it would do more harm than good, but those who have tried it swear that it sometimes works. In any case, the alternative is to junk the lens, which isn't worth the cost of professional repair.

If it is the STM version, focusing it manually in AF mode shouldn't do any damage. In that case, the problem must be something else.

[filionugo]

I'm looking to borrow an other lens to test it out. I reseted the camera to factory and it didn't change anything. I just hope that the body isn't the problem. I prefer to trash the lens. Thanks for your help!

[filionugo]

It's not the stm version so i probably killed it

[RobertTheFat]

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@filionugo wrote:
It's not the stm version so i probably killed it

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Don't give up until you've tried the "fix". The theory is that the autofocus motor gets jammed if you try to focus the lens manually while it's set to "AF". But sometimes it can be unjammed, with the lens surviving the experience more or less intact. It involves bullying the lens into submission and doesn't require any busy work with tiny screwdrivers or jewelers' loupes. Definitely worth trying.

[filionugo]

I'll definitely try to fix it. I have nothing to lose.

[Stephen]

Here's the rundown of how you can see if this is something you can fix yourself easily:

What you'll want to do is put your lens into MF mode and put the top dial of the camera into P.

Rotate the focus ring (not the zoom ring) all the way one way until it stops, then rotate it the other way. You might hear clicks, pops, or even a little bit of crunching. This is OK, but don't force anything!

Once you've rotated the focus ring either direction, put the lens back into AF mode, and put the top dial in "Green Box," "Auto," or "A+" mode, and go to a well-lit area and take a photo of something with a good amount of contrast - not a plain white wall or the sky. If your flash pops up and strobes, your camera is struggling to focus. If your subject is within 10 feet or so, the pop-up flash can help the lens to achieve focus. If it's farther than that, not so much. 

If your camera beeps, and you see a red dot in your viewfinder, or if the lens doesn't move, then it's broken.

If you get a good focus, and the camera snaps a shot, huzzah, you've fixed it! 

[filionugo]

I tried it before and tried it again and it didn't work. I sutdy electrical engineering, I'll try to open it since I don't have anything to loose and I'm going to throw de lens away anyways.

thanks

[lly3988]

No need to throw it away. Sell it locally "for parts and repair", you will get $20 to subsidize your next purchase.

It's an easy fix for DIYers.

[filionugo]

well I should be able to fix it then and if not I'll sell it for parts 🙂