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17-40 1:4 L Autofocus

winminn
Contributor

Lens is sometimes very slow to autofocus and sometimes does not focus at all.  Any suggestions what could be wrong?

10 REPLIES 10


@winminn wrote:

I have found that when the autofocus does not activate, it can help to point at something close at hand.  That sometimes helps, not always. If it "wakes up" from that act, then it seems to be okay.  However, it's still slowl


Just this lens, huh.  Some lenses do not transition well from focusing at near infinity, to focusing at near the MFD.  Your remark about “wakes up” is what brings this to mind.  Sometimes your subject can be the problem, like focusing on a bird sitting on a branch, hidden among other branches and leaves.

 

While the lens is what focuses, the camera body is what controls the shows.  Sometimes the combination of focusing mode, AF point selection, and other settings can degrade performance.  

 

You will get the fastest AF performance One Shot mode, which is what the Green [A] mode uses.  One Shot mode gives you a focus lock confirmation beep, while AI Servo does not.  

 

So, I ask what focus mode are you using?  Which AF point(s) are you using?


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