How do I set spot AF only on 5d3?

[AAPhotog]

Im curious as to how I use spot AF on the 5d3? I went to the menu and took the check mark off everything but 'spot AF' and the one next to it. But for some reason the one next to it I can't uncheck. So when I go to select an AF point when shooting, instead of selecting a small dot, Im only allowed to select one of the squares.

[AAPhotog]

I've got the nifty fifty lens on, and for some reason, when I try auto focusing about a quarter of the times it just keeps shifting(a small bit) but it never actually focuses. Why is that? I keep thinking Im too close to the subject but even when I back up it does the same thing

[Mt Spokane Photography]

Im curious as to how I use spot AF on the 5d3? I went to the menu and took the check mark off everything but 'spot AF' and the one next to it. But for some reason the one next to it I can't uncheck. So when I go to select an AF point when shooting, instead of selecting a small dot, Im only allowed to select one of the squares.

Select the small square with the dot in the center.  You can set it as the default.  As you change AF points you should see the small dot go on and off.

[Mt Spokane Photography]

I've got the nifty fifty lens on, and for some reason, when I try auto focusing about a quarter of the times it just keeps shifting(a small bit) but it never actually focuses. Why is that? I keep thinking Im too close to the subject but even when I back up it does the same thing

It can be a number of things, but when mine did that, the lens was damaged.  Put the lens in MF and carefully focus it over the entire range.  If it has spots where it hangs or is stiff, it is damaged. 
 
Try it on a different body to see if it has issues there as well.

[Ryant]

Your focus is probably shifting because you have AI Servo on. That is for tracking objects. You can switch to AI Focus or just the regular focus. Its in the manual. You can change focus types by pressing the mf function button on the top of the camera. The mf function button will only change modes after you press the focus select on the back top right of the camera. Also in the manual.

Ryan

[AAPhotog]

Your focus is probably shifting because you have AI Servo on. That is for tracking objects. You can switch to AI Focus or just the regular focus. Its in the manual. You can change focus types by pressing the mf function button on the top of the camera. The mf function button will only change modes after you press the focus select on the back top right of the camera. Also in the manual.

Ryan

Thankyou so much!!!!
I was in the actually menu checking and unchecking the focus options. What I didnt realize was, what I checked and unchecked wasn't what the camera used, it was just the options the camera had when choosing focus options(by clicking mf function button) so now I know, they way to change how the camera actually focuses is to use the mf function button lol...

[Mt Spokane Photography]

Glad you found it out, it wasn't apparent that you missed that step. 
 
You can also press the info button and then the AF point selection button on the top right back corner and see and adjust them on the rear lcd.
 
 

[AAPhotog]

Glad you found it out, it wasn't apparent that you missed that step. 
 
You can also press the info button and then the AF point selection button on the top right back corner and see and adjust them on the rear lcd.

lol yea Im slow. when I unchecked the focus options in the menu, I thought that I was changing the autofocus lol