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Exposure not working for EF 24-70mm F/2.8L II USM Lens


I have Canon EF 24-70mm F/2.8L II USM Lens that I have been using for past few years. For the past 2 days, the exposure on the lens is not working correctly. The pictures are very dark in live view mode as well as actual photo. Even when I bump up the ISO to 3200 and shutter speed to 1/10 in an outdoor area, the lighting is barely visible.


I've tried my camera with other lenses and they work fine. So, I know for sure that it's something to do with the lens. Any ideas or suggestions would be greatly appreciated. Thanks!



Sounds like the aperture is stuck.

@kvbarkley wrote:

Sounds like the aperture is stuck.

Welcome to the forum.


Yes. Is the optical viewfinder dark when you look into it? If you look into the lens from the front do you see the aperture blades? Set Av to f/22 and press the DOF button while looking into the lens - is anything moving?

John Hoffman
Conway, NH

1D X Mark III, M200, Many lenses, Pixma PRO-100, Pixma TR8620a, Lr Classic

Thank you John. The optical view finder is also dark when I look through it. Not as much as the lens but still darker than the lighting conditions in the room. I also tried setting the aperture to F/22 and present the DOF button but I don't see anything moving in the lens.


I did notice that the exposure compensation for the len is stuck at -2 and doesn't change even when I change the exposure setting to +2 in the camera.


After testing with other lenses, this has "contact canon" all over it.  The lens might require service.  

Bay Area - CA

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've tried my camera with other lenses and they work fine

It is unlikely it is a camera problem. But there are other things besides aperture blade fault. Flex cable for example. At any rate it’s a Canon issue
EOS 1DX and 1D Mk IV and less lenses then before!


As others noted, the aperture blades aren't responding so it is something Canon service will almost surely have to address.  The one "trick" that might work is set the aperture to its highest number and tap the depth of field preview button (usually to the right side of the lens mount on most Canon bodies) several times.  This is telling the aperture stepper to cycle between it wide open and fully closed settings and SOMETIMES this will unstick a stuck aperture mechanism.  I don't have much faith in it working because this is generally only sucessful with a lens that has been sitting unused for a long period of time which doesn't sound like the case with your 24-70.



EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video

Thanks for the trick Rodger but as you mentioned, it didn't work. I think my only solution would be send it out for repair.


I have the same problem that my aperture on my lens is not working. I see that the exposure settings are way out indicating a very long exposure would be required. I tried cleaning the contacts on the lens and camera but this did not help. I then tried a different lens and everything works fine. Looking through the lens I see the aperture is closed down. I initially thought that the aperture blades may not be moving freely and after looking on line I see that there is sometimes an issue with the flex cable to the aperture motor. It looks like this part is available on line for about $3.00 however to replace it requires the disassembly of the lens that is not something everyone will want to do. There is a video on this at As I do not currently know what the problem is I will probably disassemble the lens and check the aperture movement and test the aperture flex cable and replace if required.