50mm 1.8 focus problem

[JacoMedia0113]

Whenever I focus automatically with the viewfinder, it doesnt actually focus where it says it will. For example, I tested this out with a roof and focused on the chimney and saw the red flashes indicating where the camera is focusing. It also looked perfectly in focus in the veiwfinder. When I took the shot and saw where the focus point was, it was about 10 feet closer to me than the chimney. Then I went to the lcd screen and focused the same way on the chimney and it focused perfectly. I tried this on other lenses and its only the canon 50 1.8. Its really not that expensive so I might get a new one or if you recommend a better 50mm lens. I use a canon 6d btw if that helps. Thanks.

[TTMartin]

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@RobertTheFat wrote:

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@TTMartin wrote:

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@JacoMedia0113 wrote:

Yes its the stm. I would never put a bad set of glass in front of a 6d lol

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I agree 10 feet is a lot, and would seem to indicate something other than a lens issue. But, if it is a lens issue it needs to be sent into Canon for repair.

Some things to eliminate on the use side.

Make sure you are in 'One shot' focus mode.

Make sure you are in single center AF point selection mode.

Do not use Auto AF point selection, AIServo or AIFocus for your test.

Here is a more recent and in my opinion better Microadjustment Guidebook.

Canon EOS AF Microadjustment Guidebook

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It's hard to see it as a lens issue. Note that the OP told us it focuses fine in live view, so the problem must be with the viewfinder's AF. AFMA should be the first thing to try.

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Elimitating user error as a factor is the first thing the OP should try.

AFMA won't correct for a 10' error.

Liveview and viewfinder PDAF focus systems work completely differently.

I doubt it is a lens issue, but, at 10' it is also not a microfocus adjustment problem. And if it is user error, AFMA will just compound the problem. 

[ebiggs1]

"Elimitating user error as a factor is the first thing the OP should try.

AFMA won't correct for a 10' error."

"I doubt it is a lens issue, but, at 10' it is also not a microfocus adjustment problem. And if it is user error, AFMA will just compound the problem."

I ditto that. 

[RobertTheFat]

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@ebiggs1 wrote:

"Elimitating user error as a factor is the first thing the OP should try.

AFMA won't correct for a 10' error."

"I doubt it is a lens issue, but, at 10' it is also not a microfocus adjustment problem. And if it is user error, AFMA will just compound the problem."

I ditto that. 

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Whether AFMA will correct a 10-ft discrepancy probably depends on how far away the object is. Think of it as a DOF-related issue.

[jrhoffman75]

Message #13 - OP says it is fixed via AFMA.

[ebiggs1]

Robert, 

Let's think!

It's normal for AFMA to vary with distance of course. At longer subject distances, the delta becomes very small, this is why the usual recommendation is to do the test at 25x to 50x the focal length.  Let's use a 50mm f1.8 lens x 25 = 1250mm or about 4 feet.  Even at 50x it is a tad over 8 feet.  Depth of focus is actually what we are working with here.  Let's assume an adjustment of +5 on the f1.8 lens.  This might be fairly noticeable but at f5.6 or f8 hardly noticeable. Tiny corrections, right? 10 feet is a lot. Whether it is the OP's problem or not, I still think it not likely an AFMA issue..

[RobertTheFat]

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@ebiggs1 wrote:

Robert, 

Let's think!

It's normal for AFMA to vary with distance of course. At longer subject distances, the delta becomes very small, this is why the usual recommendation is to do the test at 25x to 50x the focal length.  Let's use a 50mm f1.8 lens x 25 = 1250mm or about 4 feet.  Even at 50x it is a tad over 8 feet.  Depth of focus is actually what we are working with here.  Let's assume an adjustment of +5 on the f1.8 lens.  This might be fairly noticeable but at f5.6 or f8 hardly noticeable. Tiny corrections, right? 10 feet is a lot. Whether it is the OP's problem or not, I still think it not likely an AFMA issue..

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Except that, as John points out, AFMA apparently did fix the OP's problem.

[ebiggs1]

Robert,

"AFMA apparently did fix the OP's problem."  

Yes, I know that is why I stated, "Whether it is the OP's problem or not, I still think it not likely an AFMA issue."

The reply was in response to your thought that 10 feet is a doable correction for AFMA.  I think it is out of the reach of AFMA to the point of being certain that it is.

[RobertTheFat]

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@ebiggs1 wrote:

Robert,

"AFMA apparently did fix the OP's problem."  

Yes, I know that is why I stated, "Whether it is the OP's problem or not, I still think it not likely an AFMA issue."

The reply was in response to your thought that 10 feet is a doable correction for AFMA.  I think it is out of the reach of AFMA to the point of being certain that it is.

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Suit yourself, Ernie. But as they say in the legal profession, "Rēs ipsae loquitur."

[ebiggs1]

I am not an attorney so I have no idea what that means or even how to pronounce it.  I am a photographer and still think 10 feet is not possible. But you certainly have my permission to try.

[Waddizzle]

Take a look at what the DOF table says about a 50mm with a 5D at a distance of 20 feet.

http://www.dofmaster.com/doftable.html