Points in Focus Photography

Canon 5D mark 3 top LCD Light Leak…Is it actually an issue?

Update May 1, 2012: I’ve published a preliminary report on the extent of the issue I’ve seen on my camera. Though not as scientific as I wanted it to be, it’s good enough to draw some conclusions about how and what situations could cause metering issues.

Update April 23, 2012: Canon has updated the service notice regarding the light leak situation. Canon will be offering a free inspection and adjustment on a voluntary basis if you feel your camera is operating improperly. I have to say this is about what I expected them to do. In the mean time I’m in the process of trying to put together a write up based on my findings under various conditions. Unfortunately due to limited time and equipment, I was unable to investigate to quite the level of rigor I was hoping to be able to, but even with the wider error margins from what I could do, the picture is vary clearly one of a non-issue at best, and a potential issue for a very small minority of users at worst.

Update April 13, 2012: I don’t know if I should be surprised or not, but Canon has officially acknowledged the top LCD backlight affecting the meter in certain dark environments and that they are working on a fix for it. The official service notice has been posted by Canon USA, and I’m sure if they haven’t already the rest of Canon’s global sites will have similar notices posted soon.

Update April 9, 2012: I have spent some time playing with the range where the back light causes a metering error, and so far as my limited testing shows as long as you’re operating in the EV 1 to EV 20 metering range, the meter behaves correctly. I used a 45W lamp, on an X10 lamp module, and shot at f/4 ISO 3200. The test goes something like this.

  1. Set the camera up pointed at a constant scene lit that’s lit by your dim-able lamp.
  2. Pick an aperture. Any aperture will show the change in metering, however the max aperture is what you need to look at to determine what light level exists in front of the camera.
  3. Set the camera to ISO 1600 or ISO 3200 (I used 3200, but in 1600 would probably work as well).
  4. Dim the light or adjust the angle of the camera until you meter EV 3. I used 1/15th f/4 ISO 3200.
  5. Read the meter, and switch between backlight on and off. Note if the meter changed.
  6. Dim the light until the metered shutter speed drops 1-stop. Repeat step 5.

For my test, I’ve summarized the the settings and whether the meter was affected by the backlight in the table below.

Summary of EV, shutter speed, and backlight error at f/4 ISO 3200
EV Shutter Speed LCD Backlight
Effects Metering
EV -1 1s Yes
EV 0 1/2 Yes
EV 1 1/4 No
EV 2 1/8 No
EV 3 1/15 No

Even though the meter seems to work correctly inside the designed/specified EV 1-20 range, I still think that Canon should address this.

Update April 8, 2012: I’ve been keeping up with the discussion on Canon rumors forum and my own testing and the thing is there doesn’t seem to be any real impact in metering when actually shooting. Moreover, there are a number of people reporting that they can reproduce the behavior on a huge verity of cameras including Nikon bodies. Given that, and the fact that I see virtually no difference in metering between my 5D Mark 3 and my other bodies in actual use and under conditions that are within the design parameters of the light meter (i.e EV 1-20 with a 50mm f/1.4 lens as ISO 100) I’m even more comfortable in my conclusion that this is even more of a non issue that I had initially believed.

Originally Posted April 7, 2012: Canon Rumors is reporting that there’s a potential light leak in the 5D mark 3 LCD into the viewfinder. Subsequently, at least for some it seams, the world has ended, and we should all send our cameras back to Canon, switch to Nikon, flail our hands over our heads and generally freak out.

That said, there doesn’t seem to be much of a problem in actual practical usage of the camera.

If you have a 5D mark 3, or really any other camera, you can test it for this light leak by following the procedure outlined in the Canon Rumor’s article.

I sat down and ran the test, and yes, turn the backlight on and my 5D mark 3’s meter changes when the backlight is on and both the viewfinder cover and body cap are on. Out of curiosity, I figured I’d test this out on my other bodies as well. My 40D doesn’t exhibit this behavior, even when shining a light on the LCD. However, the meter on my 1D mark 3 does change, though it requires shining a light on the LCD not the backlight.

But the real concern for me, is if the “light leak” is leaking to the sensor during an exposure or just the meter, since this would be a real problem. Fortunately this doesn’t appear to be the case at all.

1 second, ISO 25600, Light shone on top LCD
1 second, ISO 25600, No light on top LCD

Both images are uniformly black and have no noticeable localized lightening. Moreover, at ISO 25,600 even a small amount of light, never mind a 3 D-cell Maglight at point blank range if there was a light leak that effected the sensor there would be a something in those images.

So all this has the potential to do is affect the metering in practice in the real world?


Under normal use, I’m having a hard time finding a situation where there’s an change in metering that 1) I can attribute directly to the top LCD leaking and not a change in the composition, subject, eye-placement at the viewfinder, or lighting, and 2) where said error in metering is appreciable enough to affect the captured image in any appreciable way.

So far as I can tell, so long as the light levels at the camera and subject are in the same neighborhood, there’s really no impact what so ever. The only case where I can make an appreciable change by shining light on the top LCD is when it’s basically the only light the camera’s meter is seeing.

In any case, I’m certainly not all that concerned. As I already mentioned, if I shine a light on my 1D mark 3s top LCD under the same kinds of ambient conditions and I can get the meter to change as well. However, in more than two years of using that camera, I’ve never had a single exposure related problem.

So what should you do?

Well that’s up to you, but I’m going to continue to use my camera as I normally would. Moreover, whenever Canon gets around to addressing this—and I’m assuming they will—I don’t expect to be real quick in sending my camera back unless it’s also convenient for me to do so. While this certainly shouldn’t happen and it would be good to have fixed, it also doesn’t seem to be impacting my images either and that matters more than any potential problem that doesn’t quite manifest itself in real world usage.



I think my have a meter problem in manual mode.

If I take a picture for example: Manual 4.0 / 1/200 / iso 800 & I compare the same but in P mode the manual picture is a bit darker like 2/3 also you can notice that if you check the histogram.

since I start to take pictures with my 5d mark iii I notice the picture was a bit dark like 2/3 so if I want to take the picture right I have to set my meter to +2/3

    V. J. Franke  | admin

    I’m not seeing this behavior on my 5D-3, so it may very well be something specific to your camera. Mine meters identically regardless of mode, and there’s very little variation in the histogram for the same composition under the same lighting regardless of exposure mode.

    If you’re scene is not uniformly lit, can you confirm that you’re not subtly changing the composition (i.e. you’re shooting on a tripod) between test images. Or does this happen regardless of what the scene is?

Jeroen Horlings

There isn’t an issue with image quality, but there is a real issue with exposure. When shooting from the dark in any mode but M the exposure will be affected when using the lcd-light. You’ll get slightly underexposed images. See these example photos here:
(use your mouse to scroll over the photos to see the affected image)


    V. J. Franke  | admin

    There isn’t an issue with image quality, but there is a real issue with exposure. When shooting from the dark in any mode but M the exposure will be affected when using the lcd-light. You’ll get slightly underexposed images.

    When you say light leak with a camera, my first concern is whether or no that leak affects the images. It’s real easy to work around metering issues, it’s real hard to work around a light leak that affects the image directly. So that’s where I go first. The rest is gravy.

    Never mind that working around the issue isn’t exaclty difficult or impossible.

    That said, I still think Canon needs, and probably will, address the issue.

Dav Hughes

I ordered my 5D3 yesterday, and when I first stumbled upon articles declaring the light leak, my sank. But the more I read, I suspect this is not going to have an impact on the type of photography I do.

I’ll check the behaviour of my 5Diis when I get home (just out of interest).



Javier rivera

I send BACK MY 5D MARK III, I notice the same the pictures are underexposed, BUT if am not sure if is just my camera or a few cameras (I found last night some one saying the same thing from flickr) or just my camera, I download a few raw files from other people 5d3 cameras I open it with Lightroom I click AUTO fix and LR fix the exposure +0.2, another raw file +0.10, another one +0.30, my files +1.75, +1.50. if I take a picture with my meter +2/3 lightroom fix it +0.75 to +0.65.

something is wrong…. and make sence if the sensor is getting more light then you have to bump your meter a few stops and then the picture came underexposed.

I dont know I am just saying something is wrong I will like to here what canon have to say about it.

    V. J. Franke  | admin

    If all your pictures were off by 1-1/2 to 1-3/4 stops, then I’d be inclined to believe that there was a problem with your specific camera. Like any production run, there are always the possibility for defective units that slip though the quality control process.

    That said, it would have been easy enough to test if the issue was related to the top LCD by placing a piece of opaque gaffer/cloth tape over the LCD and seeing if your exposures improved. Something to keep in mind when you get your next camera, assuming you’re getting a replacement 5D-3.


there is, canonrumors had post a “recall?” “Stock Delayed?”

Like I said something is wrong, I sent mine back yesterday for a refund (faster way to get a new one than an exchange) and I was planing to order a new one today but I guess I will wait to see how this ends.

    V. J. Franke  | admin

    I saw the post, it’s too bad that Canon couldn’t/didn’t get ahead of the rumor mill even if it was “bad news” and a recall. Ya, at this point I would hold off on ordering one too until whatever is up is sorted out.

    It’s really starting to get annoying being an early adopter.

Stanley zheng

It is not an issue at all in normal photography work situation, the object and the surrounding has to be dark for it to affect the ae. Even at f4, at 2 seconds iso 800 does not affect the ae metering when u turn on the lcd top light! with the lens cap off and view finder being covered. Is this really an issue??? at ISO 800, f4, at 2 seconds no change! I am surprised that people are really hyped abt this.

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