Issue with 70-200mm f2.8l ii IS

[Richwin1]

• Need help, I have 5D mark iii with 70-200mm f2.8l ii with is. Having issue with lens when pushing focus button, focus just continuously runs in and out. I sent to canon and they were not able to find anything wrong. This happens on three different cameras, 5d mkiii, 7D, and Rebel T6. I attached a video. If anyone has experienced this issue, any help would be greatly appreciated. 

[Tronhard]

What kinds of objects were you trying to focus on, and how far away were they? 

Is it always the same objects with different cameras?

[Richwin1]

people 15 to 50 ft away. I can put on my 24-70 Lens and it works fine.

[Waddizzle]

What is the setting of your Focus Limit Switch on the lens?

[Richwin1]

It does the same thing in either 1.2 or 2.5

[ebiggs1]

"people 15 to 50 ft away."

Perhaps not the best for testing AF.

Very first top of the list. Reset the 5D Mk III, great camera  BTW, to factory default. There is a possibility you have set something off.  Clear all settings and, important, clear all custom settings.  Makes sure all the lens switches are in their default positions too. Any AF lens needs vertical lines and contrast to focus the best. After reset try using AF with the problem lens on some things with good contrast and some vertical lines. If it now works, it works and there is nothing wrong with it. If it doesn't it needs to go back to Canon and tell them how you tested it.

[Richwin1]

Reset camera and lens, still runs in and out of focus continuously. Thanks for your suggestion.

[ebiggs1]

You need to call Canon again. This time send the lens and the camera.

[Richwin1]

Waiting on Canon to reply to my email. This issue is present with the lens on 3 different cameras. Thanks again for your time and trying to help.