Back Button Focus...again.

[jpharbour]

A bit confused. 

If I am using AI Servo, and back button focus, I focus on something not moving and can release to lock focus and then recompose.

If I'm in One Shot, same thing happens.

I've been told that in that situation, the focus using One Shot is more precise than working full time in AI Servo and releasing the back button focus to lock the focus and shoot. 

Any truth to that?  (Given that both scenarios are using the same single focus point)

If they are exactly the same quality, why not (almost) always shoot in AI Servo and just release for focus lock when you have a stationary subject?.....just in case the subject starts moving again.  Much faster than switching from AI Servo to One Shot.  And save One Shot for things that won't move....landscapes, etc.

Am I confused?

[Waddizzle]

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@jpharbour wrote:

A bit confused. 

If I am using AI Servo, and back button focus, I focus on something not moving and can release to lock focus and then recompose.

If I'm in One Shot, same thing happens.

I've been told that in that situation, the focus using One Shot is more precise than working full time in AI Servo and releasing the back button focus to lock the focus and shoot. 

Any truth to that?  (Given that both scenarios are using the same single focus point)

If they are exactly the same quality, why not (almost) always shoot in AI Servo and just release for focus lock when you have a stationary subject?.....just in case the subject starts moving again.  Much faster than switching from AI Servo to One Shot.  And save One Shot for things that won't move....landscapes, etc.

Am I confused?

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One would expect the photos taken in AI Servo mode like that to have nearly identical focus to One Shot mode.  More times than not, though, the One Shot mode photo will seem sharper.  

I think it really depends upon the scenario, though.  How much is the subject moving, and how long you hold the BBF button.

[diverhank]

Once focus is achieved, the shot is sharp so AI Servo and One Shot is the same...the evidence is the wild life and Birds In Flight pictures are razor sharp and they are usually taken in AI Servo mode.

The only problem with AI Servo is you can't very easily tell where the focus point is and there is no confirmation beep...It is even worse in sports like football where there are multiple players...you can't always be sure which player it's locked on...There will be a certain percentage of shots that has the wrong focus...

One shot mode is easier that way so when you take portrait pictures and want to know precisely where the focus is at.  The only drawback is that it's not fast enough if your subject is moving at break neck speed...