Focusing issues on EF-L 70-200 f2.8 ii

[Steve6696]

Hi

I am having focusing issues using the above lens. 

I use it mainly at marathons, so I'm focusing on a runner about 50 feet away, typically taking 3 shots in burst mode and AF-C focusing. I then move to the next runner however the camera refuses to focus. At this point if I then focus on the ground near to me it will focus and then when I re focus on the next runner 50 feet away it will focus correctly again. However it won't focus for the runner after that until I once again refocus on the ground in front of me. (Hope that makes sense!) 

Its definitely a new issue with the lens as I've tried it on my 2 bodies with the same outcome.

Its not an issue with my technique using the lens as it hasn't happened on the half a million shots previously using that lens. 

I've cleaned the contacts on lens and bodies and the screws on the lens are not loose. 

Any suggestions on what's wrong or anything else I can try before looking at a repair gratefully received. 

Thanks, Steve

[deebatman316]

Does the lens always have to be pointed at something different. For the lens to AF normally. AI Servo has no focus lock. It sounds like your camera has locked focus. Which only happens in One Shot AF. 

[Steve6696]

Yes, it's almost like the only way to get the focus working again is to focus on something fairly close and then that allows for one focus further away. I'm never on one shot AF. 

[deebatman316]

Have you checked the focus distance switch on the lens. I believe all versions of the 70-200mm F/2.8 have that switch. Including my 70-200mm F/2.8 Mark III IS model has it. 

[Steve6696]

I'm certainly going to give that a look 👍

[Waddizzle]

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@Steve6696 wrote:

Thanks, yes for what I'm doing (15000 shots per race) any form of BBF would kill my thumb (as I found out early on) so I leave it off for this type of work. So shutter button does it all. This body/lens combo has worked well together for years until this weekend. 

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I was suggesting that you try setting up BBF for [AF-OFF].  

You need to force the camera acquire the subject you want.  It will not do it for you.