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Author Topic: 5D MIII - Where should it expose?  (Read 3708 times)

rossgumbrell

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5D MIII - Where should it expose?
« on: September 21, 2013, 11:37:34 AM »
Hi All,

Long time reader, first time poster. Wanted to ask for a general consensus regarding the metering of the 5D MIII.
After two weeks of use, I noticed all my photo's were looking underexposed by around a stop. Mainly interior work, evaluative metering.

This is where i've sun a series of tests to establish what was up. Removed ALO and HTP, set the picture style to neutral (good representative jpeg preview for the camera histogram) Set up an 18% grey card in even lighting, filled the frame and spot metered off it. Indeed, it came out as I expected.

The histogram spike was 1 stop to 2/3 stop too far to the left (underexposed). I repeated this test a few times with the eye piece covered, top LCD covered (even though its not a light leak effected model, thought ild be safe). Reset camera settings, did a hard reset (removed the clock battery, battery and card), then finally reinstalled the latest firmware. No change.

A search online seems to show that a fair few people experience this same thing. A theory that is posted regularly is that Canon do this intentionally to preserve the highlights. Note: in the same shooting conditions my 7D experiences no such behaviour (histogram spike is perfectly centred).

I realise I could simply dial in a +EV but its proving a tad annoying, especially when using TTL flash and I can kiss goodbye to auto ISO in manual mode. So, the question is: does anyone with this camera experience this at all?

Thanks all!

Ross

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5D MIII - Where should it expose?
« on: September 21, 2013, 11:37:34 AM »

duydaniel

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Re: 5D MIII - Where should it expose?
« Reply #1 on: September 21, 2013, 01:51:12 PM »
Professional lines cameras tend to under expose a bit.
This applies for 5D3 and 1DX as well as D800 and D4

although the 5D3 reuses the 63 dual layers metering from the 7D
I think the reason is to keep highlight. You however can set exposure bias.

DR in 5D3 is high enough to pull stuff out of darkness as well as highlight.

emko

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Re: 5D MIII - Where should it expose?
« Reply #2 on: September 21, 2013, 01:54:42 PM »
i just set my exposure comp at +2/3 or shoot manual this has bothered me a lot but i got used to it.

photonius

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Re: 5D MIII - Where should it expose?
« Reply #3 on: September 21, 2013, 02:10:51 PM »
Hi All,

Long time reader, first time poster. Wanted to ask for a general consensus regarding the metering of the 5D MIII.
After two weeks of use, I noticed all my photo's were looking underexposed by around a stop. Mainly interior work, evaluative metering.

This is where i've sun a series of tests to establish what was up. Removed ALO and HTP, set the picture style to neutral (good representative jpeg preview for the camera histogram) Set up an 18% grey card in even lighting, filled the frame and spot metered off it. Indeed, it came out as I expected.

The histogram spike was 1 stop to 2/3 stop too far to the left (underexposed). I repeated this test a few times with the eye piece covered, top LCD covered (even though its not a light leak effected model, thought ild be safe). Reset camera settings, did a hard reset (removed the clock battery, battery and card), then finally reinstalled the latest firmware. No change.

A search online seems to show that a fair few people experience this same thing. A theory that is posted regularly is that Canon do this intentionally to preserve the highlights. Note: in the same shooting conditions my 7D experiences no such behaviour (histogram spike is perfectly centred).

I realise I could simply dial in a +EV but its proving a tad annoying, especially when using TTL flash and I can kiss goodbye to auto ISO in manual mode. So, the question is: does anyone with this camera experience this at all?

Thanks all!

Ross

While it indeed may be that particular camera lines are set different regarding exposure, I guess systematic tests would be necessary - maybe something for lensrentals to confirm hearsay?

My 400D seemed to somewhat underexpose, while my 550D (same metering system as 7D) overexposed even in conditions when it should not have. In addition, I discovered a serious misalignment of the exposure meter, the center was substantially off so that the spot meter would not meter the right thing. After three trips to Canon everything was eventually fixed.  The point of this story is that it seems possible that exposure metering may also be subject to calibration variations (like accurate PD focus). Constantly having to dial in a compensation does not seem the right way to deal with this.


Eldar

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Re: 5D MIII - Where should it expose?
« Reply #4 on: September 21, 2013, 02:11:53 PM »
I have the same experience, even though a bit less than what you describe. And considering what I am able to pull out from the shade in post processing, compared to what I am loosing in the highlight areas, if the exposure is correct, I have come to the conclusion that it benefits my end result to have a slight underexposure.
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nitelife2

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Re: 5D MIII - Where should it expose?
« Reply #5 on: September 21, 2013, 02:26:12 PM »
Hi Ross,

thanks for asking this question! My 5D3 also underexposes, sometimes by more than 1 stop. I gave my body to the canon support twice because I thought it has a problem. Support told me that the body is OK as it is.
CPS is not aware of problems with metering. But there are a lot hits when you google for it.

I work around it with a user profile. Neutral and contrast -4, the other values are 0. This works much better imho.

privatebydesign

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Re: 5D MIII - Where should it expose?
« Reply #6 on: September 21, 2013, 03:20:24 PM »
The 5D MkIII meter, as all Canon cameras have for years, meters to 12% gray, NOT the 18% gray that is the normal presumption. 18% gray gives you a histogram spike in the middle stop of a histogram. BUT 12% gray gives you a spike in your histogram 2/3 stop below middle gray.

Your camera is working to specs and as it is intended. Some suggest the "underexposure" is due to digital captures being very sensitive to over exposure, but that just is not the truth, pre digital Canon's and Nikon's meter 12% too.

A more interesting question would be "why did the camera industry decide 12% metered scenes give a "better" exposure?" My answer would be that they considered the options and decided that gave more even and "correct" exposures more often than 18%.
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Re: 5D MIII - Where should it expose?
« Reply #6 on: September 21, 2013, 03:20:24 PM »

wsgroves

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Re: 5D MIII - Where should it expose?
« Reply #7 on: September 21, 2013, 04:57:59 PM »
Only had my 5d3 for a couple hundred shots so far but I did notice that every raw I opened in photoshop it did want to boost the exp a lot higher. Maybe that is unrelated however.
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nitelife2

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Re: 5D MIII - Where should it expose?
« Reply #8 on: September 21, 2013, 06:22:15 PM »
The 5D MkIII meter, as all Canon cameras have for years, meters to 12% gray, NOT the 18% gray that is the normal presumption. 18% gray gives you a histogram spike in the middle stop of a histogram. BUT 12% gray gives you a spike in your histogram 2/3 stop below middle gray.

Your camera is working to specs and as it is intended. Some suggest the "underexposure" is due to digital captures being very sensitive to over exposure, but that just is not the truth, pre digital Canon's and Nikon's meter 12% too.

A more interesting question would be "why did the camera industry decide 12% metered scenes give a "better" exposure?" My answer would be that they considered the options and decided that gave more even and "correct" exposures more often than 18%.

How does this explain the brighter exposures of ross' and my (now sold) 7D?

duydaniel

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Re: 5D MIII - Where should it expose?
« Reply #9 on: September 21, 2013, 06:32:25 PM »
Quote
The Dual-layer system overcomes this by having one layer sensitive to red/green light and one layer sensitive to blue/green light. Both these layers measure the light in their respective spectra and the metering algorithm then combines the two to provide an accurate light reading. In this way, accurate exposures can be attained in a wide range of shooting situations and irrespective of the colour of the subject being metered.

Metering algorithm
To work with the iFCL metering sensor, cameras that use iFCL metering also feature a specific metering algorithm. These cameras always measure focus with all AF points, regardless of the selected AF mode. During the exposure reading the cameras look to see which points, in addition to the selected point, have achieved or almost achieved focus.

This information lets the cameras know which part of the image is the subject. They then take metering readings from the zones corresponding to the AF points that have achieved (or almost achieved) focus and combine them with readings from all the other zones. This allows for consistent shot-to-shot exposure, even in complex situations – for example, where there are reflections from a model’s glasses.


7D and 5D3 may have slight different algorithm.

s2kdriver80

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Re: 5D MIII - Where should it expose?
« Reply #10 on: September 21, 2013, 07:05:18 PM »
I've tested both of my 5D3s (along with three other 5D3s) to my former T2i and T3i.  All of the 5D3s consistently underexpose by the same amount in a given situation relative to the Rebels.  But I've adapted.  I try to shoot a little above 0 on the light meter.  If you were shooting predominantly white walls when shooting interiors, you need to add on at least another stop on top of that to get correct exposure.
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Re: 5D MIII - Where should it expose?
« Reply #11 on: September 21, 2013, 07:06:13 PM »
Different lighting conditions can give different results.  All my cameras, in including the 1 series and 5 series expose perfectly on a average outdoor scene.  However, indoors where there is little contrast, you must adjust the exposure.  It seems to make little difference as to the make or model of camera, some lighting is just difficult for automatic exposure software.

Nancy Goodenough

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Re: 5D MIII - Where should it expose?
« Reply #12 on: September 21, 2013, 07:43:01 PM »
That explains it. It's unfortunate as I sometimes prefer to set the 5D3 and 6D to Manual to choose SS and f/stop, then Auto ISO to handle changing light. With M one can't bracket or compensate exposure. And I'd rather ETTR, not left.

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Re: 5D MIII - Where should it expose?
« Reply #12 on: September 21, 2013, 07:43:01 PM »

eml58

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Re: 5D MIII - Where should it expose?
« Reply #13 on: September 21, 2013, 08:49:17 PM »
I use both, 5DMKIII, 1Dx (previously 5D & 5DMKII), all these Cameras under expose out of the Box, "privatebydesign" I think has the bases of why re the 12% grey card, but what ever the reason, this underexposure is built in.

Take care of it by +2/3 to 1 stop EV, if your still not sure on the exposure, Buy/Borrow a good exposure meter (I use a couple of Sekonic), run some base tests, work out where your Camera is exposing, and make the adjust,ments.

I will almost always expose to the right of the histogram in any case, except perhaps when shooting studio & flash, but that's not what I do so it's rarely a problem.

Expose to the right.
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pedro

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Re: 5D MIII - Where should it expose?
« Reply #14 on: September 22, 2013, 05:47:02 AM »

Your camera is working to specs and as it is intended. Some suggest the "underexposure" is due to digital captures being very sensitive to over exposure, but that just is not the truth, pre digital Canon's and Nikon's meter 12% too.


This is very intresting information for me. I was pre-digital Contax 139 Quartz.
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Re: 5D MIII - Where should it expose?
« Reply #14 on: September 22, 2013, 05:47:02 AM »