17-35 keeps searching

rickj

rickj

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rick
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don't know if this is the right word for it but my canon 17-35 has just started to keep searching when auto focusing, seems better at longer distance but anything near and the problem starts any ideas? I have tried other lens and there fine and it is doing it on my 1D as well as the 50D so its not the camera.

Rick
 
If it had just been doing it on the 50D then i would have suggested trying the profile for that lens.
Was it ok before and has just started doing this or is it new?
Certainly seems a strange problem, i assume you are further away than the minimum focus distance?
 
Rick,

The lens is commanded to a focus distance by the body and any positional check is internal to the lens. What you describe is a classic symptom of a stuck aperture diaphram...the lens is f/2.8 but if the aperture is stuck at f/11 or f/16 then there's not enough light for the body to determine AF.

Look through the lens off the body and see where the aperture blades are....if they are stuck in a stopped down position then stick it back on a body and try toggling the DOF preview button repeatedly as it may unstick them.

Bob
 
craig it has just started doing this, did a few shoots at a freinds shop last week on the 50D and it was fine. went to take some pics of the 70-200 I am selling and it started to play up,

Hi bob I will do as you say lin a min, and see what happens (y)
 
I had a similar situation-only in reverse on a telephoto lens-it focussed fine close but wouldn't autofocus at distance. The problem was a lose outer lens element , managed to tighten the 'ring' holding it in place and it solved the problem.
 
I have tried what you said bob and it is still the same . I have however notice the inner ring by the contact pins is abit loss there is 3 very small cross head screws that need tighting . but I have nothing that small any ideas where you can get the very small scew drivers??

Rick
 
The screws are cross head size #0.....any reasonable jewellers set should have one in it (a cheap set will probably nobble the heads though)

Bob
 
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