400D Autofocus problem

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My 400D out of the blue is refusing to lock focus, instead it (and its the only way I can describe it) judders! I currently have the battery on charge and the backup battery removed form the camera in an attempt to reset it.

Any ideas what it could be?

Thanks in advance
 
aye thats the first thing I checked. I've tried the 3 lens's I have and switched each of them between AF and MF, its as though its trying to focus but cant lock so moves back and forth across the focus point.
 
What do you mean when you say it judders?

Cheaper lenses (none usm and the like) will have a juddering effect in AI Servo, but I guess you have checked that.

Edit - Never mind the above, you posted as I was posting.

If you focus manually do you get focus confirmation lights?
 
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OK, I feel so dumb!!!

I think through some random button pressings in my camera bag the AF had been set to AI Servo, which (until now) I've never used. So many thanks to Nazbit and Raymond Lin for the suggestions and solution. I'm so relieved its not a problem with my camera :cool:
 
We have all done it. There is no focus confirmation light in AI servo until you take the picture, so thats why you probably thought it wasnt focusing, while actually it was focusing constantly.

Glad its all sorted anyway. :p
 
It was indeed focusing constantley, I guess though if nothing else I've learnt another function of the camera which does ease my feeling of stupidity a litlte, cheers again :D
 
sepulchre said:
OK, I feel so dumb!!!

I think through some random button pressings in my camera bag the AF had been set to AI Servo, which (until now) I've never used. So many thanks to Nazbit and Raymond Lin for the suggestions and solution. I'm so relieved its not a problem with my camera :cool:

lol, i was out the other day and did exactly the same thing (luckily i always take the camera manual with me just in case ;) )!
 
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