Canon 100-400L - manual focus ring jammed

StewartR

StewartR

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Stewart
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Has anyone ever seen this before? I have a 100-400L which has a totally jammed manual focus ring. The zoom (which is the same ring of course) works fine, and the autofocus works fine , but the manual focus just doesn't budge at all.

Any ideas how this could have happened? Any alternatives to a quick trip to Canon at Elstree? Do you think the warranty is likely to cover it?
 
Stewart,

The manual focus ring engages with the focus group via a sleeved stud into a helical slot in the group's cylinrical frame. Rotation of the manual ring will then have the action of shifting the group based on the curvature of the helix.
I'm guessing that the stud may have come loose or that the stud is lodged in the detent at the end of helical channel.
I can email you an exploded diagram of the lens if you think it may be useful.
It may be worth a try, based on the end of travel theory, to AF at infinity and gently try to move it and then AF at MFD before trying again.

Bob
 
I have heard of this in the past as well as the tension ring jaming up, It will be covered by warranty.
 
Canon Bob said:
I can email you an exploded diagram of the lens if you think it may be useful.
Click to expand...
Mmmm... I don't really think it would be useful, because there's no way I'm taking a screwdriver to a lens that's still in warranty! But it would certainly be very interesting. Thanks.
 
StewartR said:
Mmmm... I don't really think it would be useful, because there's no way I'm taking a screwdriver to a lens that's still in warranty! But it would certainly be very interesting. Thanks.
Click to expand...
Stewart,

Document emailed to you at help@LensesForHire.co.uk

I'd assumed that warranty terms might be different for rental items...sorry.

Bob
 
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