[Reinier]

Hello fellow Photozoners,

 

I am trying to repair a Canon EOS 550D, but I am not sure what the problem is. When I try to focus the lens starts hunting, it is not the lens, because when I turn to live view and focus, then it works fine. And I have tried several lenses and they give all the same problem.

 

Does anybody have an idea what might be wrong? Contacts are clean.

 

 

Hope to hear from you.

 

Kind regards,



Reinier

[Rainer]

Hi Reinier,

 

The most obvious thing whould be some kind of dirt or lint that covers the

AF-sensors in the bottom of the mirror-chamber. So, you might put the camera

into sensorcleaning mode (mirror goes up and thereby grants access to main sensor

but also to the entry-holes of the AF sensor). Blow thoses entryholes out with a

rocketblower ... that might already help.

 

A second cause is the little piggyback mirror behind the main mirror. The one that

reflects the light onto the AF sensors. While you are already in cleaning mode, inspect

if  anything of this tiny mirror is loose. In the actual position, the tiny mirror should be

aligned with the main mirror and should not move if you shake the camera or if

you gently try to lift it. (be careful with this one!)

 

A third cause would be a loose AF-sensor (due to an impact or a drop of the camera).

If the AF-sensor is not exactly in its designated position, this wil at least lead to

malfocus ... if the AF works at all.

 

Just some thougs ... eventually helpful ... Rainer

[Reinier]

Hi Rainer,

 

Thanks for the helpful tip! I tried it yesterday and the autofocus works again.

 

I am glad the problem was so simple to solve.

 

 

Kind regards,



Reinier