Canon 5D Mark III Light Leak?

[neuroanatomist]

Such a small amount of light would be TOTALLY AND UTTERLY swamped in any real situation, with a lens on. And remember, when the camera decides what exposure to use when the shutter is fired, it does so with the lens WIDE OPEN,  before it stops down the lens and begins the exposure. So I think it would be hard to contrive a situation where the light coming in through the LCD would be anything other than negligible compared to the light coming in through the wide-open lens.

I suspect that misses the point.  It's the metering that's affected - similar to leaving the VF eyepiece uncovered when metering on a tripod.  Extraneous (non-TTL) light hitting the metering sensor results in an underexposed shot, potentially resulting in lost shadow detail.  Not saying this is a huge issue in real-world shooting, just defining the problem.

As for the severity, it's certainly true that leaving the VF eyepiece uncovered when metering on a tripod affects exposure - remember that often if there's a brightly lit subject, the camera is similarly brightly lit and the leak will still affect the metered exposure.

[altenae]

Such a small amount of light would be TOTALLY AND UTTERLY swamped in any real situation, with a lens on. And remember, when the camera decides what exposure to use when the shutter is fired, it does so with the lens WIDE OPEN,  before it stops down the lens and begins the exposure. So I think it would be hard to contrive a situation where the light coming in through the LCD would be anything other than negligible compared to the light coming in through the wide-open lens.

I suspect that misses the point.  It's the metering that's affected - similar to leaving the VF eyepiece uncovered when metering on a tripod.  Extraneous (non-TTL) light hitting the metering sensor results in an underexposed shot, potentially resulting in lost shadow detail.  Not saying this is a huge issue in real-world shooting, just defining the problem.

As for the severity, it's certainly true that leaving the VF eyepiece uncovered when metering on a tripod affects exposure - remember that often if there's a brightly lit subject, the camera is similarly brightly lit and the leak will still affect the metered exposure.

Have tried your 5D Mark ii ?
Some reported the same issue.
Also on 20/30/40D

[prestonpalmer]

Remember, in real life, taking a picture, a lens would be on the camera, and wide open. There would be no visible or significant effect on the exposure in that case; the light coming in through the lens totally dominates, and that coming through the top LCD becomes insignificant.

You are wrong.  We are seeing the change from sunlight to shadow change the exposure by as much as 1/2 stop when the shooter moves from daylight to shadow in real shooting conditions.  I can confirm this with a bright sunlit beach photo shoot yesterday.

Yes, but the lenscap is on !!!!

I can assure you my lens cap was NOT on during my beach photo shoot yesterday.  Stepping under the shadow of the palm tree significantly changed the exposure of my subjects, who were quite far away, as I was shooting with a 70-200 wide open.  When I stepped into the bright sun, (2 feet from my original spot) the subjects are dramatically underexposed.  Nothing changed on my camera, or with my subjects, except the fact that bright sunlight was hitting the LCD on the top of my camera.  I am testing this now.

[prestonpalmer]

Such a small amount of light would be TOTALLY AND UTTERLY swamped in any real situation, with a lens on. And remember, when the camera decides what exposure to use when the shutter is fired, it does so with the lens WIDE OPEN,  before it stops down the lens and begins the exposure. So I think it would be hard to contrive a situation where the light coming in through the LCD would be anything other than negligible compared to the light coming in through the wide-open lens.

I suspect that misses the point.  It's the metering that's affected - similar to leaving the VF eyepiece uncovered when metering on a tripod.  Extraneous (non-TTL) light hitting the metering sensor results in an underexposed shot, potentially resulting in lost shadow detail.  Not saying this is a huge issue in real-world shooting, just defining the problem.

As for the severity, it's certainly true that leaving the VF eyepiece uncovered when metering on a tripod affects exposure - remember that often if there's a brightly lit subject, the camera is similarly brightly lit and the leak will still affect the metered exposure.

It seems bright sunlight does indeed change the exposure significantly.  I am testing this now.  I can confirm this by theory with my bright light photoshoot on the beach yesterday.  When I was in the sun, I had to bump the exposure by as much as 1 stop, then back it down as soon as I stepped into a shadow. 

[kbmelb]

I tested my 1Ds II and my 5DII and no changes in my exposures. My 5DIII definitely has this issue.

[Viggo]

Blocked the VF completely, took one shot (in Av-mode) then put a very bright light to the top lcd, got the exact same exposure. So for me this seems only to be an issue with the body-cap on....

[Radiating]

It seems that this is a an issue with the LED's of the LCD backlight leaking light onto the metering sensor. The amount of light that's leaked is so small that in most situations it would effect exposure about 1/100th of a stop which is not noticeable to the human eye. The light doesn't leak onto the sensor so that's a non issue.

The far greater issue is when bright sunlight strikes the LCD and leaks to the metering sensor, that could noticeably affect exposure. (this is unconfirmed though)

I just tried this on my 5D II and 20D and this seems to be an issue there too. Clearly this is a small enough issue that it took 10 years to find, and everyone still took great photos, but if the LCD actually does leak light onto the metering sensor that should be fixed, otherwise, it's a non-issue. 

[tobiah]

yep in av and P etc it doesn't seem to do it... with a book over the top of the top lcd and then with a spotlight on... didn't seem to change...

to the poster who posted the video - you are moving the camera - can you show us with this on a tripod? (not that I don't believe you)

thanks

[Fleetie]

Such a small amount of light would be TOTALLY AND UTTERLY swamped in any real situation, with a lens on. And remember, when the camera decides what exposure to use when the shutter is fired, it does so with the lens WIDE OPEN,  before it stops down the lens and begins the exposure. So I think it would be hard to contrive a situation where the light coming in through the LCD would be anything other than negligible compared to the light coming in through the wide-open lens.

I suspect that misses the point.  It's the metering that's affected - similar to leaving the VF eyepiece uncovered when metering on a tripod.  Extraneous (non-TTL) light hitting the metering sensor results in an underexposed shot, potentially resulting in lost shadow detail.  Not saying this is a huge issue in real-world shooting, just defining the problem.

I think that is an understatement in real-world situations.

The huge difference in quantities of (TTL light) and (extraneous/"leaked" light) with a wide-open lens on (certainly when holding the VF to the eye, anyway - and that issue is definitely outside the scope of the present discussion anyway) means that the LCD leak is a non-issue almost always, or always. IMO.

So I stand by my assessment of the scale of the problem.

That is not to say I don't think Canon messed up; I think they have done by not incorporating better light sealing.

[neuroanatomist]

The huge difference in quantities of (TTL light) and (extraneous/"leaked" light) with a wide-open lens on (certainly when holding the VF to the eye, anyway - and that issue is definitely outside the scope of the present discussion anyway) means that the LCD leak is a non-issue almost always, or always. IMO.

What is unclear is the severity of the leak.  I don't have a 5DIII to test (and hopefully the 1D X will not have this issue).  I do know that with the sun at my back/over my shoulder, camera on a tripod, not covering the eyepiece can alter the exposure by a full stop or more (I hang the lens cap on the eyecup). 

[Alker]

Been testing inside the house (23:00 hours and pretty dark here)

With the VF covered and Lenscap on => Same issue as in the movie
With the VF covered and no Lenscap on => No issue
With the VF covered and a very very very strong led beam beamed directly on the LCd => No issue.

So in short....no issue (for me) without the lenscap.
Strange enough I never leave the lenscap on.

[Viggo]

Been testing inside the house (23:00 hours and pretty dark here)

With the VF covered and Lenscap on => Same issue as in the movie
With the VF covered and no Lenscap on => No issue
With the VF covered and a very very very strong led beam beamed directly on the LCd => No issue.

So in short....no issue (for me) without the lenscap.
Strange enough I never leave the lenscap on.

Yup, same here.. I'll try in the sun tomorrow.

[DavidRiesenberg]

Just tested in myself. With the lenscap on the issue is there (~2/3 stops) but uncovering the eyepiece has a much stronger impact (~2 stops).
Without the lenscap there is no problem, even if bombing it from up close with a strong flashlight.

[NAshby]

I tried this out on my 7D and didn't have an issue, although my friend said he had this happen with this 5D II and 5D II.

[Dylan777]

Been testing inside the house (23:00 hours and pretty dark here)

With the VF covered and Lenscap on => Same issue as in the movie
With the VF covered and no Lenscap on => No issue
With the VF covered and a very very very strong led beam beamed directly on the LCd => No issue.

So in short....no issue (for me) without the lenscap.
Strange enough I never leave the lenscap on.

Yup, same here.. I'll try in the sun tomorrow.

I'm California, right now is 2:17PM, temp at 82F, very sunny.

* Covered VF, with 50mm lens attached - NO ISSUE