There have been reports of “light leaks” with the Canon 5D MkIII. I followed the info to this article.
Canon did confirm there have been reports:
In extremely dark environments, if the LCD panel illuminates, the displayed exposure value may change as a result of the AE sensor’s detection of light from the LCD panel.
The phenomenon […] has been confirmed when using the Canon EOS 5D Mark III Digital SLR Camera. Canon is now examining the countermeasures and once the countermeasures are decided, we will post the information on our Web site.
But look at the video showing these ‘light leaks’. I did. And since I have a 5D-III I decided to recreate this ‘light leak’ as done in the video.
No lens, body cap on, set to AV, in a totally dark room. Guess what? Nothing happened. No exposure changes, no changes in settings. Also, how many photographers are going to be adjusting their cameras without a lens, with just a body cap on it?
It’s like a futz keystroke on a computer that might shut a program down. But it even more reminded me of an old GET SMART episode, where you had to sink 4 billiard balls lined up just right, in the proper pockets to get the secret transmitter built into the pool table to open up. This light leak does not happen under normal operations.
Could it be an issue? Yes. Is it a catastrophe? Not hardly.