EOS-1D Mark III Getting Large Zone AF to Stay Put

[negativeh]

Shooting sports, I use Manual select Large Zone AF. I set it in the middle. Often between plays, the setting moves to the right or left. show do I lock this in?

[deebatman316]

What focus mode are you using One Shot or AI Servo. One Shot is focus priority. The camera won't take a picture unless the AF system locks on something. AI Servo (now simply called "Servo AF" in newer cameras) is release priority. The camera WILL fire the shutter regardless if the AF system has locked or NOT. AI Servo doesn't have focus lock like One Shot does. There is another focus mode called "AI Focus". This focus mode is a hybrid mode that auto switches from One Shot to AI Servo. Depending on if the camera sees a moving subject. This focus mode is not recommended because the camera can interrupt camera shake as a moving subject. This focus mode is NOT included in high end cameras such as the EOS 1D series and the EOS 7D series. Only One Shot and AI Servo ONLY apply to your camera. AI Focus is NOT a focus mode included in your camera.

-Demetrius

Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT

Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM

[negativeh]

I NEVER use one shot.Go to the purple menu, go to the 4th option down, which is AF select mode. I use the 5th one over, you can position it in the middle, left, or right. Between plays, when often it will move left or right. How do I keep it in the middle? Applies only to EOS 1D Mark III>

[deebatman316]

I want to confirm that you are using the APS-H 1D Mark III released in 2007. Not the Full Frame 1DX Mark III released in 2020. 

-Demetrius

Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT

Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM

[Waddizzle]

Are you using the OVF or Live View?

Sounds like you either need to disable “Continuous AF” or define an “Initial AF Point”.

[EDIT] Exactly which camera are you using?  The “EOS 1D Mark III” is an old camera.

[ebiggs1]

"I NEVER use one shot."

You should! Here's what I use for sports, Av mode select the proper aperture depending on your lens. Set upper and lower limits for your SS. Use Auto ISO and set upper and lower limits. Use large Raw and daylight WB but that isn't important because you can edit in post. Select One Shot and just the center focus point. Before you do these changes reset your 1D3 back to factory default because it sound like you may have set something improperly. Don't forget to reset custom settings too.

"Sounds like you either need to disable “Continuous AF” or define an “Initial AF Point”."

It's hard to say what the OP has set or what is wrong that's why a reset is very important. IMHO, however, his setting for sports is not the best.

[negativeh]

This is all irrelevant, and I may have stated the question badly. However, I read the CanonEOS 1DX  Mark III white paper and found my answer.