Help with Canon 85 F1.2 L II and Canon 5D Mark III

[TheIndividual]

Hi All

I recently bought a new Canon 85 F 1.2 L II lens and it is giving me a troubling focusing problem with my 5D Mark III.

The focus of the lens is sharp and exact when I use the center focusing point (double cross-point) of Mark III. However, when I use any other point (cross point or otherwise) of the camera focus system, the lens either front focuses or back focuses.

Since the depth of field of the 85 mm lens is very small at F1.2, the image turns out to be completely out of focus if I don't use center focus point.

Since the center focus point works correctly, I can not use AF Micro Adjustments either. So, to the other users of Canon 85 F1.2 L II, is this a common problem or should I return the lens and try with a new copy? I am pleased with the results of the lens when it focuses correctly, but I find it hard to use only the center point all the time.

My Canon 70-200 F2.8 L II does not have any of this problem and focuses well at all cross points.

Thanks in advance.

 

[bdunbar79]

I think you'll see this exact same problem with a lot of lenses open that wide at f/1.2. I own the 85 f/1.2L II and I cannot recall where I used a point other than center I guess. What do you know, I guess I've never tried what you are trying. I will test mine out tonight.

 

[Martin]

Check on flat surface or a text. Maybe one of the side is frontfocusing and the other one is backfocusing. Maybe the lens are not properly aligned inside. I am sure if that is a good conclusion but it might be the case. I have a similar problem with one of my L lens .from my test it seems thats the lens problem. Also check on other body. If i were you i would send it back.

 

[RLPhoto]

I've used the 85LII on the 5D3. It was fantastic on all the cross-type AF points and the normal AF points were sketchy.

 

[TheIndividual]

Thanks for the responses. I have done the tests on a flat surface with a tripod.
I have noticed that most of the left side AF points front focuses and right side AF points back focuses with the lens. So, it seems it is the problem with the lens.

 

[Mt Spokane Photography]

Thanks for the responses. I have done the tests on a flat surface with a tripod.
I have noticed that most of the left side AF points front focuses and right side AF points back focuses with the lens. So, it seems it is the problem with the lens.

Not necessarily so. The AF points can also be individually adjusted by Canon and can be off just a bit. I'd send both lens and Camera in for adjustment.

 

[mingyuansung]

I have read couple similar cases for 5d3 + 85L. I have the same issue for 5D3 with 50L. I reported in another thread http://www.canonrumors.com/forum/index.php?topic=11969.0

So if it is convenient for you, you can try Canon Service center and let us know the result. Since I need to spend nearly a whole day drive back and forth there, I have not tried them. I called though.

I researched another forum and read couple other people's experiences and talked to Canon Service center. 5D3 has micro adjusted out side focus points (not center focus point) in order to fix those F1.2 lens back focus issue. This is confirmed with Canon Service center.

So my conclusion is if the lens itself has back focus issue, it will be fixed on 5D3 and perfect. If the lens has no back focus, you will get front focus on 5D3. And as well as 1Dx. The only fix is if Canon Service center would spend time to adjust your camera setting with your lens. It is a case by case issue and it does take time. So that is the reason I am afraid I would waste my time with the service center.

So I would suggest: 1. return the lens if possible. 2. try more copies if you can. people do report all accurate focus points with your combination. 3. use center focus point and crop. 4. try Canon Service center.

After spending good money and expectation, I can feel your pain. Take care.