EOS 5D mkII with 24-105mm L f4 AF problems

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My last two jobs using the EOS 5D mkII with 24-105mm L f4 have lost about 50% of the images through poor focus.

I use the centre focus point, one shot, with the expanded 'invisible' AF points disabled. Focus beep enabled & focus search after focus failure disabled. Firmware is updated to 2.1.2 & all electrical connections have been cleaned.

I set up a high-contrast & low contrast subject as a control test. The EOS 5D mkII with 24-105mm find the focus on the high-contrast subject but not on the low contrast subject. If I put the lens on an EOS 5D or EOS 400D it finds the focus on the low-contrast subject. If I put a 50mm f1.8 or 20-35mm zoom on the EOS 5D mkII it finds the focus on the low-contrast subject.

Is there an issue with the EOS 5D mkII with 24-105mm combination using the phase AF? I toggled the IS which makes no difference.

[ebiggs1]

"Is there an issue with the EOS 5D mkII with 24-105mm combination using the phase AF?"

I have use that combo a extensively over the last several years (1000's pf photos) and never seen any problems.

Other than cleaning the contacts on the camera or possibly the sensor and area, I don't know why it would not focus properly.

Maybe a C&C by Canon is in order?

[amfoto1]

Hi,

I assume you have used the combination of lens and camera without any problem prior to these last couple jobs where you had trouble. If so, have you changed anything? If so, that might be the cause.

If not, since the lens seems to work fine on other cameras, and the 5DII works fine with other lenses, it's pretty baffling.

I would have suggested things you wrote that you have already done: firmware update, cleaning the lens to camera contacts (and checking that the corresponding spring-loaded pins in the front of the camera are not sticking), and using the center AF point only.

If you haven't already done so, I'd also do a "reboot" of the camera, just to be certain there are no bad instructions "stuck" in the camera's memory.

In order to reboot the 5DII, first you need a jeweler's cross point screwdriver to get at the little time/date memory battery that's on the lefthand side of the camera (right below the various input/output sockets). Use the screwdriver to remove the single screw that keeps the small battery drawer in the camera. Turn the camera off. Remove both batteries. Switch the camera on and press the shutter release button once. It won't fire, of course, but this will drain any remaining power in the circuitry and should force the camera to reboot. Switch camera back off and reinstall the batteries. Then turn the camera back on check the date/time. If it needs to be reset, you got a proper reboot. If not, try again. If it still doesn't reboot, try leaving the batteries out overnight.

There are no guarantees... In fact I suspect it's rather unlikely to help with a focus issue. But it's free and easy to try, and sometimes it helps with various issues.

Enabling the "assist points" or not shouldn't matter at all. Those only work in AI Servo mode. You wrote that you are using One Shot mode and those additional points will not function.

Turning IS on or off also shouldn't matter. Some people swear IS makes lenses focus more slowly. I think it actually helps with accuracy and focus speed.

One thing though... Are your test shots and the problem shots on the job done on a tripod? If so, the 24-105 is one of the lenses where IS needs to be turned off if the camera is solidly mounted on a tripod. If there is no movement, the IS can go into sort of a feedback loop that causes movement. The overall blur this causes can look like missed focus.

I have never heard of a specific problem with the 5DII and 24-105 combo.

Hope this helps! Keep us posted.

***********
Alan Myers

San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & PRINTROOM

[20pictures]

Thanks for the feedback...

Will try a reboot as this is the only suggestion I haven't already tried (did a function reset).  Tests were handheld (as were the last 2 jobs which suffered from image losses).

I mentioned the assist point as I did try all the AF focus modes to see if it resolved the issue.

I am a bit baffled too ...as there seems no logic to the test results!

One point that seems unlikely but worth a mention. I recently used a Yongnuo ST-E2 flash controller with AF Assist. It stopped working second time I used it & is currently in China being repaired. Is it possible that a 3rd party accessory could corrupt the Canon AF in the way I am experiencing? I will report on the hard reset.

[ebiggs1]

Over the years I have heard of every conceivable calamity possible blamed on 3rd party off-brand accessories. Now whether true or coincidence remains elusive. So the answer is, yes. But not proven.

As always it is best to use Canon equipment with Canon equipment.

[20pictures]

I have discussed it with Canon UK & Fixation repairs.

The only advice I could get was tinkering with the sharpness in the various custom functions. Not ideal. Needless to say, they both recommended a full body service.

It looks like this is what I will do...

[cale_kat]

@ebiggs1. I notice that you use Lightroom with your Canon. So an Adobe product is OK but not a Yongnuo product? I'm trying to follow your logic in this example which involves AF electronics.

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I not sure I follow the Lightroom connection. 

When shooting I use no tethered software, only what is in-camera. I mentioned the Yongnuo as I was using its AF Assist when it 'died' on the camera. It has just returned from China where they have reinstated its ability to fire a speedlight but not to control the light output.

I am resigned to a full camera service.

[cale_kat]

If the problem is a software issue, which is what would be suggested for a focus accessory causing selective (it only troubles the OP in low contrast scenarios) auto focus trouble, then it's a corruption or virus issue. I think it's just as likely you could bring that on through memory card use. At some stage you're inserting a compact flash card into a card reader and tether with a computer. Reuse of that card carries the same risk, possibly much higher, of creating corrupt files or bringing a computer virus into the camera.

I only remarked on the Lightroom because it's in your signature and it is so popular with photographers.

[ebiggs1]

You may have a point about the memory card but it isn't possible for the camera to get a virus. Unless you consider some firmware swapping Trojan. It just doesn't have the necessary resources to process a virus. Plus there are so many different internal workings of DSLR's it isn't practicable.

At the very least, I have never heard of a camera being infected with a virus but ..........................