canon EF-S 18-55 random auto focus problem

[Terryrebelt2i]

Hello

I have been working with Canon EF-S 18-55 NON IS lenes and have found a problem I can't seen to solve. The problem is that I do get auto focus but at certain points it will not focus. I have changed the board with a known good one, The motor assembly, The contacts with good looking ones from working units but not the contact strip as they look good.

The assembly moves freely with little resistance. I have also seen this problem on IS versions too but mainly on the non IS versions.

I'm looking for any other suggestion that might solve the problem.

[ebiggs1]

Does this indicate you disassembled the lens?

[Terryrebelt2i]

Yes I do and have had very good success in repairing them but I have a few that just defy me and have this problem.

[ebiggs1]

Man I don't know.  It could be anything if you got inside.  You are braver,  than I.

[Terryrebelt2i · Accepted solution]

Well I finaly figured out what the problem was and fixed 3 lenes.

[RobertTheFat]

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@Terryrebelt2i wrote:

Well I finaly figured out what the problem was and fixed 3 lenes.

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And what did you find the problem was?

[Terryrebelt2i]

The problem is with the focus flex cable. Right at the mounting point of the flex cable the constant flexing has cause a micro fracture of the copper traces that allowed intermittent disconnection. You could not see the problem unless you removed the flex cable and then examined it under a 200x power scope. Replacing the flex cable solved the problem.

[kathiemo]

Terry..

I am having this intermittent auto focus problem with my 17 – 55mm F2.8 with Image Stabilization. It will focus at the full zoom and as you zoom in the focus will blur out..I can hear the motor attempting to focus and then it won’t. It is unusable at this point and obviously needs repair. I really hope I can afford to fix it, I shoot as a volunteer for a small public high school. This is a great go to lens for shooting with available light . Do you think I will need to mention this as the possible problem? I don’t want to offend anyone.

[RobertTheFat]

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@kathiemo wrote:

Terry..

I am having this intermittent auto focus problem with my 17 – 55mm F2.8 with Image Stabilization. It will focus at the full zoom and as you zoom in the focus will blur out..I can hear the motor attempting to focus and then it won’t. It is unusable at this point and obviously needs repair. I really hope I can afford to fix it, I shoot as a volunteer for a small public high school. This is a great go to lens for shooting with available light . Do you think I will need to mention this as the possible problem? I don’t want to offend anyone.

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A similkar (but I think not identical) problem with the 17-55 has been reported in this forum within the past few months. It must be fairly rare; both my wife and I have had 17-55's for several years and have not experienced it. But it could be what's happening to you. If you decide you want to mention the problem when you send the lens in for repair, you could go through the lens threads for the past three or four months and see exactly what was said.

[ebiggs1]

Bob from Boston,

True I have no first hand knowledge with the EF-S 18-55 but I will guess it is nearly a throw away lens.  At $200 bucks for a new version II, I mean.  Yes, no?