# FPS drop using back button focus technique



## alexanderferdinand (Jun 15, 2013)

5d3 with 135/2L.
I am getting used to the back button focus - technique.
AI Servo, focus with the AF-ON button, leave the button, if focus is achieved.
Slight recompose necessary: ok, move a bit, klick.
Works fine.

The only thing that I don't understand:
FPS is set to High, but when I shoot a few pictures in a row it falls of to - estimated- 3 FPS.
When my thumb stays on the AF-ON button, FPS is normal.

Can somebody explain this to me? 

Thanks a lot.


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## RGF (Jun 17, 2013)

alexanderferdinand said:


> 5d3 with 135/2L.
> I am getting used to the back button focus - technique.
> AI Servo, focus with the AF-ON button, leave the button, if focus is achieved.
> Slight recompose necessary: ok, move a bit, klick.
> ...



Have you set the camera AI Servo 2nd image to focus or speed (Under AF, 2 menu group, 2 line). If you select Focus speed will be sacrificed for accurate focus, if you pick Speed, focus is sacrificed for speed. Or you could pick the mid point. Press the INFO button for more info


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## alexanderferdinand (Jun 17, 2013)

Thanks a lot. I know, I have selected priority more accuracy, less speed.

I will check this.

Thank you very much for this hint!


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## alexanderferdinand (Jun 18, 2013)

Dear RGF!

Checked, tested and you were right!

The thing I don't understand: if I "disconnect" the AF from the shutter, why does this causes this effect?
The AF is "fixed" after leaving the rear button. So there is no such thing, that AF or FPS has priority....
Hm.

Anyway. It works.
And I say thank you for this very helpful hint.

Greetings from Austria, alexanderferdinand


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## RGF (Jun 18, 2013)

Alexander

Glad it worked. Software in cameras is a strange beast. 

Enjoy the camera. You live a beautiful country.

Rich Fisher
Outside Chicago (USA)


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