Is this an Hardware issue? (Lens Can't Autofocus)

[iskoos]

Hi there,

I got a lens from a friend. He pretty much gave it to me. It is a USM Canon mid range zoom lens. It autofocuses and works alright till you pass certain (around 50mm) zoom range. At longer range, the lens keeps trying to autofocus but it cannot. The focus confirmation light(yellow dot) blinks and you do not hear the confirmation beep. Thus camera doesn't take any picture.
Lens works fine at wide angle end (50mm and wider). This only happens when I use 50mm zoom or more.
I tried all autofocus modes; the result didn't change. I know my camera is okay because I do not have this issue with my other lenses.
When I use manual focus, I can focus on anything at any zoom range with no problem and focus confirmation light comes on. So problem is when I pass 50mm point.

So am I looking at a hardware problem here? Is this a common problem?
And is it fixible? I really liked this lense and I would be willing to spend some money to fix it...

Thanks

 

[CoRNDoG R6]

That's probably why he gave it to you! It's most likely broken. I thought maybe you were having focusing problems cuz of low light conditions, but I read your post and your having issues after the 50mm range...so it's obviously a different problem.

 

[Overread]

It could be AF problems because of lighting if the lens has a variable max aperture - ie its max aperture at the wide end is greater than its max aperture at its long end. That might explain why it can't get an AF lock on if you are inside and in dimmer lighting conditions.
However if you are testing outside in good lighting and you are still getting problems then there is likey and issue. First thing to do is clean the lens and camera contacts - that is the little copper coloured metalic parts on the inside of the lens housing on the camera and on the camera mount of the lens. If that does not solve the problem then there could very well be a defect on the lens itself.

 

[gsgary]

I'm with Overead, pilot error

 

[iskoos]

Yeah. I thought about low lighting factor at first but no excuse after shooting outdoor almost all day today...

Dirty contact points!.. Wish I could be that optimistic

Will seek technical assitance. I am not giving up on this lens yet...

 

[donki]

did you solve this problem? I have exact the same thing....

 

[KmH]

Do you have the same shooting conditions?

 

[iskoos]

Wow!.. I am replying to such an old thread but I just realized that there were other posts after my last one. I don't like to leave the threads I started without the conclusion.
Yes, I fixed this issue. I sent it in for repair. Canon service found a defective ultrasonic ring motor and replaced it. The cost (parts and labor) was $100 plus shipping. Since I didn't pay anything for the lens, I decided it was worth having it fixed. It has been working like new since then (almost 2 years) and it has been my all-around lense. The zoom range is perfect for everyday use. The ultrasonic motor autofocusing and IS are big step up from the stock kit lense of 18-55mm. The only limitation of it is not being fast enough especially at the long end (just f/5.6). But I think this one was a kit lense as well shipped with certain Canon DSLR cameras...

 

[KmH]

:thumbup:

 

[table1349]

Geez....................this thread is like so two years ago.