EOS 850D: Auto focus with shutter issue, back button focusing

[BENCAR]

The Auto Focus in my EOS 850 D only works now if I use the button on the back of the Body, not by depressing the Shutter Button.

[stevet1]

BENCAR,

I own an 850D too and I'm sorry you are having trouble with it.

But using the back button focusing is not necessarily a bad thing. I personally use it exclusively all the time.

Are you having any difficulties?

Steve Thomas

[BENCAR]

It is a problem, especially if I hand the Camera to a novice or I'm shooting a moving car, or Locomotive. Worse, it just stopped functioning, and the Camera is only 3 months old.

[Tronhard]

Hi Bencar and welcome to the forum:
Cameras do not come new with Back Button Focus configured to the exclusion of the shutter button, so is this camera a used one that you have purchased?  The camera can be reset to factor conditions that return focus to the shutter button, but the concerning issue is that you say it has stopped working.
Do you mean that literally?  If so, where did  you purchase this from and is it under some kind of warranty?

[BENCAR]

New in box, not intended for U.S. Sale.

[stevet1]

BENCAR,

By default, cameras come with their focusing assigned to the shutter button. Did you, by chance, go into the Custom Function settings of your Menu system (the ones that look like a little wrench), and take your focusing off the shutter button?

If you did, then no, the shutter button will no longer do the focusing for you.

As far as moving objects go, if you press down on that back button and hold it down, the lens will continue to focus as long as you keep it pressed down. You can follow a moving train, or a child running, and keep them in focus all the time.

If you press the button once and let go, your lens will focus once and then stop focusing until you press it again.

The latter approach is handy if you want something off to the side of your picture to be in focus, but not necessarily what's in the center.

Steve Thomas

[Tronhard]

Mind you, for that to work, one must enable SERVO focus mode.  I'm still concerned by the statement that the camera has actually stopped working.  I would like to get that statement clarified...

[BENCAR]

It hasn't stopped working,  add I'll recheck the settings. 

[BENCAR]

Also,  my 4th in the Rebel series, never had Auto Focus just decide not to work.

[Waddizzle]

If you have purchased a used camera body, then you should reset the camera back to its original factory settings. You want to begin using the camera with all settings in a known state.

A complete and thorough camera reset can take 10-15 minutes, so you should begin with a fully charged battery. Keeping the rear display active for that length of time as you browse through the menu system can be a significant drain on your battery.  

But first, this is how to restore AF to the shutter button.  We want to reset any and all Custom Controls programming.

Switch the top dial to “P” mode.  Press the [Q] button to open the Quick Control Menu. Navigate to the icon that looks like a camera and select it. 

This shortcut should open the Custom Controls menu.  I believe there should be a garbage can icon at the bottom of this first page. Select it to clear out any existing programming. 

Retest your Shutter button.  Hopefully, it should be working normally now.  By default, the rear button that you were using also starts the AF and Metering systems.