The Light Leak Issue
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Read this elsewhere.
Read it and think about it.
This leak thing with cap on is BS.
These lens cap on tests are ludicrous beyond belief.
They involve light levels far beyond the meter's range of operation. The meter is designed to produce an image that is 18% grey. Does anyone seriously think that the meter reading in these tests, with or without the LCD light, are registering 18% grey.
Add to that the fact that the EV scale is non-linear and it's hard to see how a rational, informed person could get so hysterical about this. The quantity of light required to shift exposure by 1 stop at these levels becomes a tiny fraction of a stop at real exposure levels - probably less light than leaks into the viewfinder past your eye - and much much less if you happen to look through the viewfinder wearing glasses.
Read it and think about it.
This leak thing with cap on is BS.
These lens cap on tests are ludicrous beyond belief.
They involve light levels far beyond the meter's range of operation. The meter is designed to produce an image that is 18% grey. Does anyone seriously think that the meter reading in these tests, with or without the LCD light, are registering 18% grey.
Add to that the fact that the EV scale is non-linear and it's hard to see how a rational, informed person could get so hysterical about this. The quantity of light required to shift exposure by 1 stop at these levels becomes a tiny fraction of a stop at real exposure levels - probably less light than leaks into the viewfinder past your eye - and much much less if you happen to look through the viewfinder wearing glasses.
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justsomedude said:
If you turn a bright light on during a long exposure, you will have 10,000 more times light leaking thru the lens than the lcd. Set your exposure before opening the shutter, in fact, I don't believe you can set a different exposure once the shutter is open. Try that and let us know how it works.
BTW, last evening, I had tried some of the same tests that Craig did and found the same results. It is very difficult to block all light from entering the viewfinder, holding it to your eye lets enough light in to change the exposure slightly as you move from shadows to direct sunlight. However, even with a very bright led flashlight, and even the bright sun on the top LCD, I could not cause a change in exposure when the viewfinder was totally blocked.
I seem to recall someone doing the same test on the 5D MK II 4 years ago, it had no effect on mine the past 4 years, and does not affect exposures on my 5D MK III.
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so is the light leak "only to the light meter" or "to the sensor too"?
because I can live happily with the former, but the later would be a killer (I like stars timelapses)
because I can live happily with the former, but the later would be a killer (I like stars timelapses)
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Thanks for testing so thoroughly Craig. Basically the same results I found when trying to "leak" into an actual lens-cap-off exposure. I just can't force myself to get concerned over P-mode shots of the back of the lens, because I only do that when I'm REALLY drunk
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msdarkroom said:
Actually... this is probably the best explanation I've heard so far. The 5D3 does seem to be MUCH more sensitive to dark situations than any other body I've ever had the pleasure of trying. I'd be very curious to see if the 1DX also does the same thing in idiotic lens-cap-on tests.
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justsomedude said:
The only thing this appears to affect is the meter; it doesn't affect the exposure at all. I just don't see how this is going to be of any relevance. Do you really meter the night sky? Or do you take a test shot and see what it looks like? For that matter, with experience, I'd expect the exposure to be known and consistent.
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bp said:
The image sensor has nothing to do with the metering settings on the display. The metering sensor is under the mirror and is used to set aperture and shutter speed. This means light is getting to the metering sensor. Obviously, if it gets to the metering sensor, then it probably gets to the main sensor as well, its just not very much light.
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L
Lstop-photo
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I have also notice a2/3rd of a stop difference on the 5D3. When I received the new camera I tested the exposure against gray targets, just to see how the new metering system was faring. I have noticed the same difference in my everyday shooting, and have set the cam at +2/3 pretty much consistently.
I don't know if this is related to the light leaked issue or simply the way the new metering system behaves, but I would be interested in knowing if other people have noticed.
Luc
I don't know if this is related to the light leaked issue or simply the way the new metering system behaves, but I would be interested in knowing if other people have noticed.
Luc
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javier
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Lstop-photo said:
Ok thanks I now know I am not crazy and this actually happens.
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
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javier said:
First do the test with the lenscap off.
With me and others including the test of CR no issue at all.
The metering is not responding to any light at all.
Test this first before you think there is a real problem with the 5d mark iii
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TrumpetPower! said:
Maybe I've been taught the wrong way, but I've regularly used the camera's metering system for astrophotography. By ramping up to a high ISO (say 3200), and performing a short exposure, you can then calculate back out to an equivalent exposure at 100 ISO using a bulb. But if your initial "base" (for calculating) exposure is wrong, your 3-hour equivalent will be shot, and no one likes to waste three hours under a night sky.
Granted, most astrophotographers will thoroughly check the LCD and histograms before moving forward with a longer exposure - it just sucks knowing that the initial calc made off the LCD display may be totally bogus.
This isn't really a deal breaker - since most longer exposures are done manually - it just means the LCD could be useless for performing one's exposure calcs. Kinda crummy, especially since that LCD backlight is invaluable in the hills when its pitch black. Looks like I'll just have to use the LCD preview and INFO screen instead, once the test exposure is complete.
Meh.
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Read this on FM and I think he is 100% right.
this finding of a purported light leak on the 5D3, is typical of this stage of the life of a new camera model, in a world where too many buyers of such stuff are nerds rather than photographers (I confess being a nerd myself):
someone sets the camera up in a weird way, ie blocking any light from entering
this someone apparently doesn't realise that this means any further "experimenting" will be basically measuring noise.
But doing so in ways much less useful or professional than the manufacturer would
the same person then proceeds to flash a light at the camera. Woooo, apparently a tiny bit of that light gets in!
Should one therefore panic?
Yes if the person regularly (1) shoots in very very very very low light, and (2) regularly flashes strong lights at their camera while shooting in these conditions.
WHO does this? NO ONE. Astrophotographers DO shoot in very very very low light (not THAT low - nowadays any decent DSLR can capture say Orion, hand-held).
But they do NOT flash lights at the camera while shooting.
Camera makers are of course happy with any additional sale made - but frankly one sometimes wishes there were more photographers out there, and less failed testers / nerds. Puh-lease!
this finding of a purported light leak on the 5D3, is typical of this stage of the life of a new camera model, in a world where too many buyers of such stuff are nerds rather than photographers (I confess being a nerd myself):
someone sets the camera up in a weird way, ie blocking any light from entering
this someone apparently doesn't realise that this means any further "experimenting" will be basically measuring noise.
But doing so in ways much less useful or professional than the manufacturer would
the same person then proceeds to flash a light at the camera. Woooo, apparently a tiny bit of that light gets in!
Should one therefore panic?
Yes if the person regularly (1) shoots in very very very very low light, and (2) regularly flashes strong lights at their camera while shooting in these conditions.
WHO does this? NO ONE. Astrophotographers DO shoot in very very very low light (not THAT low - nowadays any decent DSLR can capture say Orion, hand-held).
But they do NOT flash lights at the camera while shooting.
Camera makers are of course happy with any additional sale made - but frankly one sometimes wishes there were more photographers out there, and less failed testers / nerds. Puh-lease!
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It sounds like a good way, but from what you describe it seems you are using the test exposures to compute the longer exposure time, not the camera metering system. Thus you would not be affected by this "light leak".justsomedude said:
It's funny how when the 60Da was surprisingly released last week, people were complaining about the lack of Canon leaks. There is really no way to please everyone :
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Loswr
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Mt Spokane Photography said:
The metering sensor was under the mirror in old designs, but these days it's actually up in the pentaprism housing (labeled in the upper right of this diagram taken from a Canon tech report):
So, light that reaches the metering sensor should be blocked from hitting the image sensor by the mirror when it's flipped up during the exposure.
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