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Re: 6d Focusing Problems

"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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Re: 6d Focusing Problems

[ Edited ]

@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.


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.

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Re: 6d Focusing Problems

[ Edited ]

@Bryston3bsst wrote:

Can you post some examples? I would like to see the missed focus shots and where exactly you originally focused before you recomposed.

 

Someone mentioned above that ' you can never get precise focus using focus and recompose'.

 

This is nonsense. I do it all the time with my 6D, I did it all the time with my 600D. It is a very common practice used by most all photographers, professionals and amateurs alike with perfect success.

 

It almost sounds like you have the camera set to AI Servo.....so when you try to recompose it will focus on the new target.

 


It works if you recompose and take, let's say, one step backwards. Or if your camera front focus. Or if your DOF is enough.

 

http://michaelfryd.com/posts/Focus-recompose-diagram.jpg

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Re: 6d Focusing Problems

"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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Re: 6d Focusing Problems


@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?


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


@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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Re: 6d Focusing Problems

"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.

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Re: 6d Focusing Problems

[ Edited ]

It is also possible to use Hasselblad and only use one (you can only use center) focus point and recompose. H4D uses distance/(cos θ) to correct the focus shift after recomposing.

 


@Waddizzle wrote:

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


Same as my 6D has...well,  not built into it.

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Re: 6d Focusing Problems

[ Edited ]

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.

 


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

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Re: 6d Focusing Problems


@Waddizzle wrote:

"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 do, usually.

Bob
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Re: 6d Focusing Problems

"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.

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