6d Focusing Problems

[perklax]

Hello,

I've recently purchased a 6d. It's a great camera and I love the look it has, but I'm having all sorts of troubles focusing. I mainly do portraits, and that requires me to consitently hit sharp focus on the eyes. For the life of me I can't do that. I'll focus on the eye using the middle autofocus point and then will recompose and take the picture, but it still won't work. It works half the time, but that's not good enough at all. It's been driving me crazy and I can't confidently go into a shoot. I'm getting paid for shoots also, so this isn't acceptable. 

[Waddizzle]

"It is not nonsense and it depends on the depth of field you have. With an 85mm f/1.2 @ f/1.2 on a full frame camera you have such a razor thin depth of field that you'll never get a sharp eye, by focusing on an eye and recomposing." 

Since we're not talking about an f/1.2 lens, I don't see your point.  Besides, the "plane of focus" should be more cylndrical than flat for most lenses, unless you're talking about a macro lens, which should have a flat plane of focus. 

I suspect that the camera simply could be inadvertently refocusing on a new target when the shot is recomposed.  It's very easy for your finger to lose your 'focus lock".  Like I said, I have been on a Back Button Focus binge of late, just for that reason.  I cannot hold the shutter button halfway, and then move the camera at the same time, very well.

[TTMartin]

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@Waddizzle wrote:

@"It is not nonsense and it depends on the depth of field you have. With an 85mm f/1.2 @ f/1.2 on a full frame camera you have such a razor thin depth of field that you'll never get a sharp eye, by focusing on an eye and recomposing." 

Since we're not talking about an f/1.2 lens, I don't see your point.  Besides, the "plane of focus" should be more cylndrical than flat for most lenses, unless you're talking about a macro lens, which should have a flat plane of focus. 

I suspect that the camera simply could be inadvertently refocusing on a new target when the shot is recomposed.  It's very easy for your finger to lose your 'focus lock".  Like I said, I have been on a Back Button Focus binge of late, just for that reason.  I cannot hold the shutter button halfway, and then move the camera at the same time, very well.

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The point is you can not get PRECISE focus using focus and recompose, period!!!

The plane of focus is not cylindrical. 

And even a Canon 6D and an 85 mm f/1.8 lens (which the OP was talking about)  has a shallow enough depth of field for focus and recompose to throw the focus off.

[Waddizzle]

"The point is you can not get PRECISE focus using focus and recompose, period!!!" 

You won't get PRECISE focus using the camera's AF system, either.

Okay, let's play it your way.  What is the proper way to focus and recompose?  Or, are you saying is should never be attempted?

[TTMartin]

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@Waddizzle wrote:

"The point is you can not get PRECISE focus using focus and recompose, period!!!" 

You won't get PRECISE focus using the camera's AF system, either.

Okay, let's play it your way.  What is the proper way to focus and recompose?  Or, are you saying is should never be attempted?

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No I'm not saying focus and recompose should never be used. What I am saying is that you can never get PRECISE focus when doing so.

So if you need PRECISE focus, you need to use an alternative method. There is a reason Pro cameras have over 60 AF points instead of just one. You can use the closest AF point to where you need the focus to be. 

Or

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@RobertTheFat wrote:

 If you're shooting in a studio with a tripod, you might find that you get better results using live view and manual focus.

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[Waddizzle]

"So if you need PRECISE focus, you need to use an alternative method. There is a reason Pro cameras have over 60 AF points instead of just one. You can use the closest AF point to where you need the focus to be. " 

Somehow, I don't think that is the primary way how the extra AF points are used.  Sure you can use them that way.  But who does it that way looking through the viewfinder, anyway?  I'm sure some folks do, but I'd bet not that many.  It takes time to switch points, not unless you have it set to switch between two pre-determined AF points, which once again takes time and forethought to set up.

Like I said, if you want "PRECISE" focus, then you are not going to get it by using the camera's AF system.  You might get close using AF, but it won't be "PRECISE."  As you pointed out, use Live View, or some other manual focusing method to get precise.

OFF TOPIC:  Did you know that the EOS M3 has focus peaking built into it?  It's a fantastic little camera.  Forget G-Series.

[TTMartin]

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Waddizzle wrote: 

Somehow, I don't think that is the primary way how the extra AF points are used.  Sure you can use them that way.  But who does it that way looking through the viewfinder, anyway?  I'm sure some folks do, but I'd bet not that many.

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I bet it is way more than you believe. It really doesn't take that long to select an AF point.

[Waddizzle]

"I bet it is way more than you believe. It really doesn't take that long to select an AF point." 

"Doesn't take that long," is still too long.  Besides, if someone wants your "PRECISE" focus, then no one is going to use the AF system in the camera. 

Not until you're dealing with very wide apertures, I don't see what difference focusing and recomposing is going to make, compared to using multiple AF points.  Besides, the cameras enable special features when you use just the single center point, anyway.

I'd bet that number of people randomly switching AF points is far less than you might believe.

[TTMartin]

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@Waddizzle wrote:

Not until you're dealing with very wide apertures, I don't see what difference focusing and recomposing is going to make, compared to using multiple AF points. 

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Exactly, and that is exactly when the OP started having problems. When he was using the EF 24-105 f/4L IS kit lens, no problems. Then he gets the EF 50mm f/1.8 STM and the EF 85mm f/1.8 USM and he starts having problems. The bad technique of focus and recompose that he developed with the kit lens, can't be used with the wide aperture primes.

[perklax]

I only use the primes actually. Never had the zoom. But when shooting vertically oriented portraits, I usually have to focus with the outermost one, which has almost always caused a soft image. 

[TTMartin]

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@perklax wrote:

I only use the primes actually. Never had the zoom. But when shooting vertically oriented portraits, I usually have to focus with the outermost one, which has almost always caused a soft image. 

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You need to be aware that on the 6D that is not a cross type focus point. It is only sensitive to contrast in one direction. Normally with the pupil of the eye being round this is not an issue. But, you should visually confirm the focus in the viewfinder. And as already mentioned, that AF point is larger than what you see in the viewfinder, so it may be picking up on the eyebrow, instead of the eye.