EF 17-40mm f/4 L USM Autofocus Issue

[Explorer0863]

Hello,

I hope that any of you can provide some direction. I was going to use this lens with my 5D Mark II this morning and noticed that the autofocus wasn't working. Checked and double checked my settings and didn't find anything wrong with them. My son has the same 5D Mark II camera body and I tried the lens on his camera. Same result. AF not working. He also has an old 20D so we decided to mount the lens and try it. The AF worked perfectly.

I was thinking that it could be a custom function that I changed without realizing that I was changing something, so I cleared all custom functions. Same result, AF not working. We tried other Canon and non-Canon lenses on both 5D M2 cameras and the AF worked fine with the other lenses.

When I go to the menu, under Peripheral illumin. correct., the camera shows the correct lens attached.

Is it possible that I am missing a setting that makes the AF stop working? The lens was working fine with this camera, and it works fine with my son's 20D. I'm stumped and any suggestions will be greatly appreciated.

[RobertTheFat]

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@Explorer0863 wrote:

Hello,

I hope that any of you can provide some direction. I was going to use this lens with my 5D Mark II this morning and noticed that the autofocus wasn't working. Checked and double checked my settings and didn't find anything wrong with them. My son has the same 5D Mark II camera body and I tried the lens on his camera. Same result. AF not working. He also has an old 20D so we decided to mount the lens and try it. The AF worked perfectly.

I was thinking that it could be a custom function that I changed without realizing that I was changing something, so I cleared all custom functions. Same result, AF not working. We tried other Canon and non-Canon lenses on both 5D M2 cameras and the AF worked fine with the other lenses.

When I go to the menu, under Peripheral illumin. correct., the camera shows the correct lens attached.

Is it possible that I am missing a setting that makes the AF stop working? The lens was working fine with this camera, and it works fine with my son's 20D. I'm stumped and any suggestions will be greatly appreciated.

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In this context, the principal difference between a 5D2 and a 20D is the latter's smaller sensor size. I haven't thought it through or tried to do the math, but how close was the subject on which you were trying to focus? Could it have been outside the focus range of that lens on a 5D2? Did you try to focus manually at that distance?

[Explorer0863]

I was outside, landscape photography. Switching to manual focus I'm able to turn the focus ring and take pictures.

[Mark35mmF2]

Hey there,

It sounds like you may have the autofocus decoupled from the shutter button as you had said. This would not change when clearing the camera setting because button assignment is a separate function. to test this, the AF-ON button should still allow for autofocus.

Under custom function menu IV, setting 1 labeled "Shutter Button/AF-ON button" you will want either option 0 or 1 in order for AF to be linked to pressing the shutter button.

[ebiggs1]

The first setting to clear all settings would have corrected it.  The clear all custom settings would not. Do the clear all settings option.

[Explorer0863]

I did the clear all settings option. The AF with this lens still doesn’t work.

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@ebiggs1 wrote:

The first setting to clear all settings would have corrected it.  The clear all custom settings would not. Do the clear all settings option.

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[RobertTheFat]

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@Mark35mmF2 wrote:

Hey there,

It sounds like you may have the autofocus decoupled from the shutter button as you had said. This would not change when clearing the camera setting because button assignment is a separate function. to test this, the AF-ON button should still allow for autofocus.

Under custom function menu IV, setting 1 labeled "Shutter Button/AF-ON button" you will want either option 0 or 1 in order for AF to be linked to pressing the shutter button.

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That option isn't lens-specific, is it? I believe the OP said that shutter-button AF was working fine with other lenses.

[Explorer0863]

Correct. The AF shutter button works fine with other lenses, including non-Canon lenses.

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@RobertTheFat wrote:

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@Mark35mmF2 wrote:

Hey there,

It sounds like you may have the autofocus decoupled from the shutter button as you had said. This would not change when clearing the camera setting because button assignment is a separate function. to test this, the AF-ON button should still allow for autofocus.

Under custom function menu IV, setting 1 labeled "Shutter Button/AF-ON button" you will want either option 0 or 1 in order for AF to be linked to pressing the shutter button.

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That option isn't lens-specific, is it? I believe the OP said that shutter-button AF was working fine with other lenses.

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[Explorer0863]

Hi,

When I pressed the AF On button on both camera bodies, it didn't focus. I switched the CF from 0 to 1 and viceversa and that didn't work either.

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@Mark35mmF2 wrote:

Hey there,

It sounds like you may have the autofocus decoupled from the shutter button as you had said. This would not change when clearing the camera setting because button assignment is a separate function. to test this, the AF-ON button should still allow for autofocus.

Under custom function menu IV, setting 1 labeled "Shutter Button/AF-ON button" you will want either option 0 or 1 in order for AF to be linked to pressing the shutter button.

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[stevefoobar]

I thought I was having exactly the same problem initially, however, after trying the lens on my old 20D body the lens had exactly the same problem as it does on my 5D Mark II camera body. It appears to be auto-focusing (I hear the motor trying and the lens does move in and out of focus) but unfortunately, the lens stops auto-focusing after a couple of tries and usually is left in an out-of-focus state. When I switch to manual, there are no problems.

Based on this test and this thread, I will have to assume that it's the lens. Too bad. The cost to repair at Canon is probably higher than the used resale value of the lens.

I guess for starters, I'm going to have to watch the many YouTube videos on supposed DIY Canon auto-focus lens fixes.