Tested a few cameras
I went into the office today and did some tests on all the Canon DSLRs I had in stock and discovered a few things.

The biggest discovery I found with most of the cameras and the sunlight test is that just placing your thumb over the viewfinder isn't enough. Bright light passes through the thumb without much issue. I discovered this when I used a folded piece of black fabric and stuffed that over the viewfinder. Most of the Canon cameras no longer had a “light leak” issue.

I tested with both the lens mounted with a cap on and with just the body cap on.

These tests were done in direct bright sunlight.

lightleak 575x431 - The "Light Leak" Update
The cameras I used for testing. I even mounted the same model lens on all the bodies, the 24 f/1.4L II.

Canon EOS 60D
I tested 2 bodies and found no issue once I placed the folded black fabric over the viewfinder. No change with backlight on.

Canon EOS 7D
I tested 2 bodies and found no issue once I placed the folded black fabric over the viewfinder.  No change with backlight on.

Canon EOS 5D Mark II
I tested the one body I have in stock. This camera exhibited the same issue as the 5D Mark III in direct sunlight, however the backlight didn't affect exposure. I also did the flashlight test that is mentioned below and nothing changed in exposure.

Canon EOS-1D Mark IV – Body #1
There was an ever so slight shift in exposure with the viewfinder cover down.  10 seconds out of the sun, 8 seconds in the sun. I stuffed the viewfinder with the black fabric and there was no change. The variance in exposure went away if I wrapped the LCD with the black fabric and only left enough space to see the exposure number. No change with backlight on.

Canon EOS-1D Mark IV – Body #2
This body exhibited no movement in exposure. No change with backlight on.

Canon EOS 5D Mark III
I only have one body to test for the moment, however it exhibits the shift in exposure  with the backlight turned on.

Once I placed the black fabric over the viewfinder instead of my thumb, the variance in exposure decreased in direct sunlight. However it was still present. Out of direct sunlight, the camera metered 10 seconds, in the direct sunlight the camera metered 1 second.

The final test I did with the 5D Mark III was take the lens cap off and meter off a relatively neutral wall. I turned on the backlight and nothing changed. I then pressed a 130 lumen flashlight up against the top LCD and the exposure didn't change. I also ran the flashlight around the camera body and absolutely nothing changed.

So why do things change with the caps on?
I have no idea, none, ziltch!

So is this an issue?
On the body I tested, it doesn't appear to be. If the camera acts properly with the lens cap off, who cares how it acts with the caps on? So please don't return your 5D Mark IIIs, or cancel preorders or overreact. This “issue” may have a simple explanation.

However, if Canon says something is wrong, I apologize…… it just doesn't appear there is an issue to me.


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