1DS 3 losing focus during One Shot lock

[Louis]

Hello All,
and sorry to bother you all with such old problems now you are enjoying all your new latest models I have a question, I recently bought a 1DS 3 that I am extremely happy about, apart from a small problem, I noticed that when I am using the centre point AF, and one One Shot, the camera will sometimes, lose the lock of focus even though I am holding the trigger down, so I would focas on something, then recompose and the camera would then focas on the middle of where I have just composed too, even though my trigger had remained the same, this does not happen all the time, its like the camera was telling me that it wasnt happy with where it was focussed and then redid it, but by the time that happened I had moved, I rand Canon repair and they said, are you sure your not in AI Servo and I am sure, they said its £150 to get a full service,
Have any of you ever heard of this problem do you think there is some setting I have that is doing this?
Thanks for your help, once I get this sorted I will be extremely happy

Louis

 

[Bosman]

Louis, Id google this and do some searching you may just find what you are looking for. On the other hand to have CPS clean and check everything for a couple hundred bucks, you can't go wrong. I totally though you were in servo when you described it. The fast primes do not like focussing in servo when the subject is static else i'd keep things in servo. Instead i choose servo when i need to get moving subjects. Anyway Hopefully you can give us a good report on the resolution to the problem.

 

[Mt Spokane Photography]

A dirty internal of the switch could be the cause. I presume it was a used body, Its best to have it serviced, as a intermittent switch will only get worse.

 

[Louis]

Thanks for your reply s guys

 

[cpsico]

I like to disable focus from the shutter button and only use the AF-on button in the back, this should easily solve your problem.