USM Focus Motor "Hangs"

Has anyone had any experience with a USM lens motor hanging up? My 24-70L sticks every so often at the half-press. When I half press a multitude of times, it takes a step at a time & eventually gets down to the macro area of focus and loosens up to move through the range freely. Then it hangs again. It's as if it's obstructed but the ring moves freely with no audible friction of an abnormal nature.

I know it's going in for service for sure, but I'm curious anyway as to whether anyone else has experienced it and what the solution ultimately was (other than a generic "replaced USM motor module").

In advance: don't give me suggestions as to how I should troubleshoot, folks. I'm not looking for assistance there. I've been through that already.

Believe it or not I have my 40d set to act like this.

You can tell it in custom function 3-1, not to start autofocus if it can't detect contrast. The setting is called
C.Fn III:Auto focus/Drive
Lens drive when AF impossible
0: Focus search on
1: Focus search off

Default is 0, which allows the lens to hunt, I have it at 1, which will do what you describe, it just won't move until you point it at something with more contrast or use the FTM to get it close enough that it decides to try to focus itself. So if you have the lens cap on and press AF-ON nothing happens, it does not even try to focus. I find it saves me time as if i know as soon as I press the button that contrast is too low for autofocus I can go straight to manual (standard or HSM lenses) without messing about with 3 lots of hunting first.

I figured you probably would know about this if you changed it, but felt the need to point it out just in case it would save your lens a trip to the lens doctor.

There's no such function on the 1D II, and my other lenses do not exhibit the same behavior.

cdifoto wrote in post #6887659
There's no such function on the 1D II, and my other lenses do not exhibit the same behavior.

Wouldn't P.Fn-14 do that on a 1DMkII?

Any special settings would apply to all lenses, not just one. And you cannot accidentally set a personal function. That requires being tethered. Three hours before it started hanging up, I was shooting with it with zero ill effect. Nothing happened between those two events, other than setting the camera down and picking it back up.

Like I said, it's not troubleshooting I'm after. It's definitely the lens. I've narrowed it down to that, and the behavior I'm experiencing is not a functional one that would serve a purpose. It's malfunctioning. Period.

I would appreciate the troubleshooting help, if I needed it. However, I am not confused as to what is happening. I know the lens and I know the camera. They're my bread & butter. I am simply asking if others have had this experience.


Note to mods: If people continue to show that they cannot read and/or comprehend the English Language, please lock this thread. Thanks.

cdifoto wrote in post #6887824
Any special settings would apply to all lenses, not just one. And you cannot accidentally set a personal function. That requires being tethered. Three hours before it started hanging up, I was shooting with it with zero ill effect. Nothing happened between those two events, other than setting the camera down and picking it back up.

Like I said, it's not troubleshooting I'm after. It's definitely the lens. I've narrowed it down to that, and the behavior I'm experiencing is not a functional one that would serve a purpose. It's malfunctioning. Period.

I would appreciate the troubleshooting help, if I needed it. However, I am not confused as to what is happening. I know the lens and I know the camera. They're my bread & butter. I am simply asking if others have had this experience.


Note to mods: If people continue to show that they cannot read and/or comprehend the English Language, please lock this thread. Thanks.

Not very gracious are you?
With so many posts I'd have thought that you would have learnt some forum etiquette by now.
As it is if you only want sympathy or understanding for your lens troubles, not help and advice I suggest you make that much plainer in your original post, then we can all save ourselves a lot of time and trouble in not responding to you and trying to help.

There was another thread, not too long ago, about someone's 28-70L that was doing the exact same thing. In fact, they described it almost exactly like you did, as though it were going in steps at a time, instead of smoothly.

If I can find the thread, I'll post it.

I've never had this happen to any of my glass though.

Found it . You can thank me by getting a 35L for shipping, I'll PM you my address.

https://photography-on-the.net/forum/showthre​ad.php?t=613188

PaulB wrote in post #6887929
Not very gracious are you?
With so many posts I'd have thought that you would have learnt some forum etiquette by now.
As it is if you only want sympathy or understanding for your lens troubles, not help and advice I suggest you make that much plainer in your original post, then we can all save ourselves a lot of time and trouble in not responding to you and trying to help.

Graciousness isn't in cdifoto's nature. If it were, he wouldn't be God's gift to women (err... I mean to photography. *Thinks about that*. No, actually, I did mean women ).

Damn I can't believe I didn't see that thread. Thanks Perry. Too bad his problem is still unresolved as well.

PaulB wrote in post #6887929
Not very gracious are you?
With so many posts I'd have thought that you would have learnt some forum etiquette by now.
As it is if you only want sympathy or understanding for your lens troubles, not help and advice I suggest you make that much plainer in your original post, then we can all save ourselves a lot of time and trouble in not responding to you and trying to help.

The "assistance" I've been provided is akin to someone asking for a lens under $300 due to budget constraints and being recommended every $1000+ optic with a red ring around the end of it.

I'm not gracious to "assistance" that really isn't. My opening post explicitly stated the kind of "help" that I did NOT need. I saw it coming, tried to nip it in the bud, and it STILL came.

If you actually read my post(s), you'd see that it's not sympathy I want either. I cannot possibly make what I was looking for any plainer than I already did. I can type words but I cannot make you read & comprehend them.

perryge wrote in post #6887965
Graciousness isn't in cdifoto's nature. If it were, he wouldn't be God's gift to women (err... I mean to photography. *Thinks about that*. No, actually, I did mean women ).

Then I shall ensure that I keep clear of this God's gift to whatever in the future.
What cdifoto obviously has not learnt yet - or at least won't admit - is that the more you think you know is when you start to realise exactly what you don't really know.

PaulB wrote in post #6888042
Then I shall ensure that I keep clear of this God's gift to whatever in the future.

Please do.

PaulB wrote in post #6888042
What cdifoto obviously has not learnt yet - or at least won't admit - is that the more you think you know is when you start to realise exactly what you don't really know.

I'm not here to get into a pissing match. However, when I say I know it's not my camera bodies, I know it's not my camera bodies.

Perry's link proves this.

You may think you're helping by offering up wild-ass guesses, but you're not.

cdifoto wrote in post #6888072
Please do.

I'm not here to get into a pissing match. However, when I say I know it's not my camera bodies, I know it's not my camera bodies.

Perry's link proves this.

You may think you're helping by offering up wild-ass guesses, but you're not.

As some-one had offered a C.Fn as a thought, I took it a stage further with a P.Fn.
I most obviously apologise for not been aware of your consummate skills and knowledge.

Face it though, the lens is in need of a new USM, surely even you, with all your knowledge and wanting reassurance that this isn't the problem can see that - assuming of course you have eliminated EVERY other possibility.

PaulB wrote in post #6888988
Face it though, the lens is in need of a new USM, surely even you, with all your knowledge and wanting reassurance that this isn't the problem can see that - assuming of course you have eliminated EVERY other possibility.

??? He knows that the lens needs a new USM! He isn't looking for reassurance that it isn't the problem.

He just wants to survey whether or not others have had this problem...is that so hard to understand? I got it, which is why I posted the link. No need to get offended.