Help with Focus!

[agulliver]

Hi everyone! I need some help on focusing. I have a Canon 5D Mark iii as well as a 50 1.2mm lens and am not seeming to get near the same quality photos as what I see from others with the same equipment. I am not a professional and still learning but I feel like I know enough to be getting much sharper/better focus photos. This photo below was shot at f/3.5 and I am not understanding why her entire face let alone both eyes would not be in focus?

[kvbarkley]

What is your focus mode?

The camera tells you what you are focusing on. If that is not what you want, you need to adjust things so that it is focusing where you want.

In this case, load the image in DPP, and it will show you where the focus points were.

[agulliver]

kvbarkley
I use Al Servo and placed the single focus point directly on her eye. At f/3.5 shouldn't her whole face be in complete focus?

[ebiggs1]

"I use Al Servo One Shot and placed the single focus point directly on her eye."

In this case you need to be using One Shot.  You need to have just the center focus point active.  Turn all the others off.

Shoot in Raw and do your edits on post.

[coachboz68]

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@agulliver wrote:

kvbarkley
I use Al Servo and placed the single focus point directly on her eye. At f/3.5 shouldn't her whole face be in complete focus?

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This shot was with my 70-200 on a FF 1DXII.  I just cropped the relevant section for you to see.  The girl's eye is sharp, as that's where I was focusing.  But the boy is very slightly out of focus as he was standing just a few inches behind her.  Take a guess at the apeture setting.  

This was shot at 140mm zoom at f/5.6 1/125.  The boy was not moving.  But I was standing very close relative to the zoom of the lens.  I am 100% positive there is nothing wrong my my lens or camera focus system.  It's DOF plain and simple.  That's why I'm suggesting you take out those chess peices (or whatever) and do some testing.  Based on this thread, my guess is that you will be surprised at some of the results.  Use ONE SHOT and SPOT FOCUS when doing your tests.  

[coachboz68]

I can't expand the image to get a closer look, but I'm guessing on closer inspection you are saying one eye is in focus and the other is softer?  My guess is that it is a Depth of Field (DOF) issue, which isn't really a "problem" but rather just how things work.  If you are very close to your subject, then even at f/3.5 you will have a shallow DOF.  For example, at 4ft away with f/3.5 on a 5DIII your DOF is going to be somewhere around 3-4 inches.  What I would recommend is setting up some objects on a table (like chess pieces or whatever) and stagger them by a few inches in depth across from each other.  Then setup a tripod at some given distance from which you think you will be shooting most portraits with that lens.  Then go through your aperture ranges all the way from f/1.2 to something like f/8.  Then look at those results to understand the DOF from that distance.  When I started using better lenses and cameras, this frustrated me, too.  But the fact that you have one of her eyes in focus to your satisfaction likely means it's not a mechanical focus propblem, but rather just DOF.  That's my guess anyway.  My betters on here will likely have different opinions.  

[agulliver]

coachboz68

Yes that's correct, one eye is in focus and the other is not and I would assume that at f/3.5 she should be in complete focus. Maybe like you said I was too close, I will definitely practice more with depth of field. I appreciate your advice!

[ebiggs1]

All and all you shot is pretty nice as is.  Consider these facts, the ef 50mm f1.2L operates just like any other 50mm lens when it is off of f1.2.  The 5D Mk III is just like any other FF camera.  So these issues are moot. 

One possibility you may be seeing is a front or back focusing problem.  Generally this is not a problem until you shoot something like a beautiful girl up close. Adjusting the focus does not change how sharp a lens is.  It simply adjusts the critical focus point.  You can do a simple test to confirm this.

And, another possiblilty is, are you doing a lens correction in post?  This is something you should do on all your shots. I like to use a mask and just sharpen the area where it is important.