# 40mm Pancake Malfunctioning?



## TAF (Jul 21, 2012)

Folks;

I got my 40mm pancake earlier in the week, and had been enjoying it on my 5D3.

But tonight, it simply wouldn't focus, and made a most peculiar sound. I switched lenses and everything was fine, so I assumed it wasn't the body. Then I put the 40 back on and it worked. A little time later, after turning the camera off then back on, it didn't work again. I removed it and immediately put it back on, and it was fine (camera off...but cycling power did not reset the problem).

I haven't experienced any problems with any other lenses (24-105L, Sigma 50f1.4, Canon 28f1.8).

Sounds like it needs to go back to Canon...anyone else having this problem? Could it be a user issue?

Thanks!


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## DanielG. (Jul 21, 2012)

This happened to my 40mm once, too. Same fix (removing the lens).
Hasn't happend again, since.

To me it sounds like a software bug. Focusing on the 40mm is electronic and removing the lens cuts the power.


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## suburbia (Jul 21, 2012)

It has happened to me twice, both times in low light conditions so i started thinking it couldn't focus in low light and was a bit disappointed but the mount removing worked. It was also after some wet conditions outside so was thinking that maybe a reason.


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## pdirestajr (Jul 21, 2012)

Happene to my 40mm once too. Just wouldn't focus. I took it off and remounted, and haven't had the problem since.


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## mjbehnke (Jul 21, 2012)

Brother has a T4i and the 40mm Pancake... Has had no problems at all with it and he is using it a lot. I have used the 40mm on my 60D and it seems to have the focusing issue. I really think it's an issue that Canon will need to resolve in firmware updates. My guess is it's got to do with the STM focus system and compatibility with cameras other than the T4i. That's just a guess..


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## DianeK (Jul 21, 2012)

You are not alone. See the following discussion:
http://photography-on-the.net/forum/showthread.php?t=1203463
Diane


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## spinworkxroy (Jul 21, 2012)

Do you manually force the focus ring back in? 
This will cause the lens to "hang"…
Somehow the STM "remembers" it's position and if you force it in manually wiht the camera off..when you turn it back on, the lens will somehow not work…


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## peederj (Jul 21, 2012)

spinworkxroy said:


> Do you manually force the focus ring back in?
> This will cause the lens to "hang"…
> Somehow the STM "remembers" it's position and if you force it in manually wiht the camera off..when you turn it back on, the lens will somehow not work…



That's lame if so. I would consider that a bug. Putting the camera in your bag is likely to force the barrel in and having that disable your lens is not acceptable.


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## DianeK (Jul 22, 2012)

Just focus on something in the distance so the barrel is completely in before putting the cap back on.
Diane


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## neuroanatomist (Jul 22, 2012)

DianeK said:


> Just focus on something in the distance so the barrel is completely in before putting the cap back on.



I just half-press the shutter (which is metering start only for me), then manually focus to infinity.


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## terrellcwoods (Jul 22, 2012)

I have the EXACT same issue. Periodically it just won't focus in AF. I unmount the lens...put it back on then it works...time for return I guess


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## 51m0n (Jul 22, 2012)

Happened to me once about 3 weeks ago, after I took several shots at the minimum distance and using different focus points. As other, I remounted and it is fine till now.


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## dr croubie (Jul 23, 2012)

I've had that too, the AF just stopped responding, switching to MF didn't work, then some combinations of power off-on and un-remounting the lens makes it work again.

But that was on my EOS 3, I just figured there was some bug with that, given that it's a 14 year old camera with a 2 month old lens.
Never had the problem with my 7D, although i've barely used it on my 7D much, it's made for FF/street more than crop. (Meanwhile, I should get my first processed films back some time this week, to see how 'street' it really is)


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