rear focus

I read many blog and post about rear focus ...
I love it but I hve also a questin about its validity:
When I I shot taking up the mirror
and the AF sensor can not see anything and resume operation
when the mirror goes down (by holding down the shutter button
the middle or the AF button on the back), at which point the goal is
is still with the setting fire of shot and if the subject
has not moved too much AF should not have trouble
replace it.
Not knowing how it actually did so in detail
system can at most assume that the continuous pressure on the button
AF of the back face as quickly reactivate the AF sensor, although
it seems strange given that the AF is active from half-press
the shutter button, then clicking and going halfway does not
should change anything, and even more so if you are shooting at
burst by holding down the way down the shutter button ...
In general, therefore I think it's a choice to make depending on how you
is comfortable, except technical differences and undocumented
possibly unintended by the designers.

Is right this consideration ?
And so what you think about ?

Hi Giovanni, not sure I understand your question. Are you talking about AF during mirror lock-up (in which case Liveview would be used), or how AF is affected during the mirror's movement in "normal" use?

Here's what Robert O'Toole says, if I may, regarding back focus "AF-On has a huge advantage over front button focus when photographing action because the camera’s AF system can track the subject continuously and does not have to re-acquire focus after each single release or burst of the shutter" He is referring to Nikon cameras here. I have recently switched to this method and I believe the above is true. My Nikon D300 with the 80-400 tracks much better with this method IMO.

Hello Daniel
I think I made a mistake...when you are prefocus the mirror is down ...
Thanks for your reply.
About rear foocus what you think about ?

Giovanni, Nobody is understanding your questions. Please try to explain your question to someone who knows English well and have them type it so that we can try to help....

Thanks Arthur but this is not a problem it was only a discussion about rear focus with a people ...but not worry I have no problem.
Only a question .. When I shot on the tripod I use a shot's calble soit is not possible rear focus ...off course

Still confused :).

I try again
Is possible use rear focus with a Cable remote shutter release ?
Thanks
Gio

Quote:

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Originally Posted by Giovanni Frescura

I try again
Is possible use rear focus with a Cable remote shutter release ?
Thanks
Gio

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Thanks! Now I understand the question. What camera body? I do not know but I will try to find out.

Canon Eos Mark IV
thanks
You on the tripod use rear focus ?
And not use remote shutter realese?

Quote:

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Originally Posted by Giovanni Frescura

Canon Eos Mark IV. thanks. You on the tripod use rear focus ? And not use remote shutter realese?

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I use rear focus all the time both when hand holding and when working on a tripod. I never ever use a cable release. For very long exposures I turn IS off, go to Live View (for mirror lock), and set the self timer.

I will try to find out the answer to your other question....

thanks a lot Arthur

You can always use rear focus on the back of the camera for focussing and then wait and use remote shutter releasewhen ready to open and close the shutter to capture the image.

ok thanks..it is right!