April 17, 2014, 01:26:38 AM

Author Topic: Why higher end camera underexposes images?  (Read 5485 times)

privatebydesign

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Re: Why higher end camera underexposes images?
« Reply #15 on: September 16, 2013, 10:05:19 PM »
Canon cameras, and they are not alone, do not meter at 18% grey, they meter at 12% grey, that is 1/2 stop underexposed for a mid-toned subject.

Take a picture of a grey card on an auto setting and the histogram should have a spike 1/2-2/3 stop below the midpoint.

There is no 18% law, never has been. It was just a number that represented Zone V in the Zone system. Camera manufacturers use 12% as a metered norm for the simple reason that they believe that gives a more consistently "correct" exposure.

Read the small print on a Kodak grey card to see the verbose wriggling even the mighty Kodak do to try to expose an 18% grey card with a 12% meter.
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Re: Why higher end camera underexposes images?
« Reply #15 on: September 16, 2013, 10:05:19 PM »

neuroanatomist

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Re: Why higher end camera underexposes images?
« Reply #16 on: September 16, 2013, 11:19:29 PM »
...even the mighty Kodak...

Are they really still mighty?   ;)
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privatebydesign

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Re: Why higher end camera underexposes images?
« Reply #17 on: September 16, 2013, 11:33:01 PM »
...even the mighty Kodak...

Are they really still mighty?   ;)

No, not now, but they were when they came up with so much of the stuff we take/took for granted in photography. How many companies have their own nuclear reactors in their R&D departments for instance........

How the mighty fall, imagine Apple only making cases and accessories for Samsung phones.
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Pi

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Re: Why higher end camera underexposes images?
« Reply #18 on: September 17, 2013, 04:35:02 AM »
Canon cameras, and they are not alone, do not meter at 18% grey, they meter at 12% grey, that is 1/2 stop underexposed for a mid-toned subject.

In evaluative mode, 18% or 12% means very little. In my experience, Canon's FF cameras are too protective of the highlights. Once you get used to this, it is OK.

Martin

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Re: Why higher end camera underexposes images?
« Reply #19 on: September 17, 2013, 05:56:17 AM »
Canon cameras, and they are not alone, do not meter at 18% grey, they meter at 12% grey, that is 1/2 stop underexposed for a mid-toned subject.

Take a picture of a grey card on an auto setting and the histogram should have a spike 1/2-2/3 stop below the midpoint.

There is no 18% law, never has been. It was just a number that represented Zone V in the Zone system. Camera manufacturers use 12% as a metered norm for the simple reason that they believe that gives a more consistently "correct" exposure.

Read the small print on a Kodak grey card to see the verbose wriggling even the mighty Kodak do to try to expose an 18% grey card with a 12% meter.


Why the spike should be -1/2 or 2/3EV from center? Take professional external light meter like Sekonic, take other camera (nikon) and check where is the spike. Why do u think it is correct to have the spike more on the left side. That means underexposed image in terms of standards of course. Only Canons meter in that way.
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alexanderferdinand

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Re: Why higher end camera underexposes images?
« Reply #20 on: September 17, 2013, 06:50:55 AM »
An observation using the 1d4 and the 5d3 same time and light situation:
The 5d3 sets the histogram always very left. Only if contrast is high, then its in the middle.
I do not understand this strategy, because:
The 1d4's histogram is always "well centered".
PP the RAWs of the 1d always needs less shifting the EC in the converter.
So in my case: the 1d comes closer to my result  ending with a print.

Viggo

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Re: Why higher end camera underexposes images?
« Reply #21 on: September 17, 2013, 06:54:57 AM »
The higher end camera let's you change it if you don't like something. I have bumped my 0 EV up quite a bit, because I like my images brighter exposed.

I'm sure if I factory reset my camera I won't like it all. The beauty is that I don't have to use it like Canon might have thought I would like to use it.

And the 1d X metering is by far the best I have used.
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Re: Why higher end camera underexposes images?
« Reply #21 on: September 17, 2013, 06:54:57 AM »

Mt Spokane Photography

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Re: Why higher end camera underexposes images?
« Reply #22 on: September 17, 2013, 11:36:54 AM »
The point of this thread is not about how you expose your images.
There is no standard. Some prefer darker/lighter... etc. we can talk about this for 100 years
without conclusion.

I just wanted to theorizing some reasons why manufactures adjust the cameras the way they do.
By high end cameras, I meant D4 and 1Dx.
It seems like both NiCanon slightly under exposed the image a bit when the light metering at the middle.
Maybe I am too old school but I enjoy technical stuff


I think that the old "standard" exposure was to aim for 18% grey. That was just an arbitory choice, as I understand it.  ;D

If Canon and or Nikon now think 20% grey would be better it could be for all sorts of reasons. But all sorts of possible ideas are possible, and many people will be convinced they know why. To my mind I can't think of anything more likely than preserving highlights, and I like to do that. But many people like to ETTR, so I guess they don't worry so much about their highlights.

I was advised, by a professional that I respect, to over expose bright scenes and to under expose dark ones. This was to compensate for the "standard" exposure and to make the image more life like.

 
Actually, Canon and Nikon are said to use the equivalent of a12% gray reflectance target. They use rear illuminated targets per the ANSI standard, so the 12% number is the equivalent value of a 12% gray reflectance target.  As always, info from the internet may be incorrect, but this is from a person with lots of inside contacts.  This equates to 1/2 stop lighter than the 18% targets, so someone using a 18% gray target to determine if their camera is exposing correctly will see a 1/2 stop difference.
 
http://www.bythom.com/graycards.htm

privatebydesign

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Re: Why higher end camera underexposes images?
« Reply #23 on: September 17, 2013, 12:24:31 PM »
Why the spike should be -1/2 or 2/3EV from center? Take professional external light meter like Sekonic, take other camera (nikon) and check where is the spike. Why do u think it is correct to have the spike more on the left side. That means underexposed image in terms of standards of course. Only Canons meter in that way.


No Nikon also use the 12%, or very close to it, equivalent.

http://www.bythom.com/graycards.htm

Edit: I notice now Mt Spokane has already pointed some of you disbelievers to the same authoritative link. I love it when the myths and memes that people thought they understood collapse around their feet and their real knowledge gets taken to a higher level. Roll on the learning, and lest you think I think I am better than any of you, I don't, I am just at an age when I know I don't know it all, many of my presumptions are wrong, some of the people I learnt from were wrong too; but I am not so old I keep forgetting it :-)
« Last Edit: September 17, 2013, 12:30:11 PM by privatebydesign »
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duydaniel

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Re: Why higher end camera underexposes images?
« Reply #24 on: September 17, 2013, 12:48:26 PM »
These 12% is interesting but how does it explains
consumer grade cameras expose differently from higher end ones?

In metering articles, the latest Nikon use 3D matrix III metering which
looks at your scene and compares it to 30,000 images database to guess the best exposures

Meanwhile all Canon beside the 1Dx use the dual 63 layer zones.
The 1Dx uses what I think is similar to Nikon that is having a lot of sensors (100,000 rgb sensors)
and run them through some algorithms to guess the exposure.

One thing disappoints me is that Nikon lets you influence the metering system using AE micro adjustment
from the D7000 when Canon only lets you do so in the 1D series

privatebydesign

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Re: Why higher end camera underexposes images?
« Reply #25 on: September 17, 2013, 01:08:07 PM »
These 12% is interesting but how does it explains
consumer grade cameras expose differently from higher end ones?

In metering articles, the latest Nikon use 3D matrix III metering which
looks at your scene and compares it to 30,000 images database to guess the best exposures

Meanwhile all Canon beside the 1Dx use the dual 63 layer zones.
The 1Dx uses what I think is similar to Nikon that is having a lot of sensors (100,000 rgb sensors)
and run them through some algorithms to guess the exposure.

One thing disappoints me is that Nikon lets you influence the metering system using AE micro adjustment
from the D7000 when Canon only lets you do so in the 1D series

Even the most basic matrix metering system uses a fuzzy logic to guestimate what you are trying to shoot, it is the main reason die-hards (and slide film shooters) had such issues with matrix metering when it came out, you really don't have a clue what the camera is actually doing. The other metering modes are predictable because they don't try to work out what the scene "is" they just use illumination values, either as a center weighted average, a scene average or a spot average.

So as a specific answer to why cameras appear to meter differently, if they do, I would suggest this answer;
  • People that buy lower model cameras don't necessarily know what they are doing, factory default is matrix metering (semi intelligent) and it works to get a "correct" exposure because of that intelligence. High end cameras assume a higher level of understanding and exposure knowledge and the weighting of the "intelligent" part is less as the operator is expected to have a better grasp of exposure and the amount of compensation they actually want.
  • Alternatively, matrix metering nails it (and it does most of the time apart from exceptional lighting situations) so is plenty good enough for everybody, but, there was such a backlash from some pros when it first came out the "intelligent" part was eased back in there cameras metering algorithms because pros are troglodytes and too slow to embrace "new" metering systems.

Maybe try exposing a Kodak card, which is known to be 18%, with a 1 series and a Rebel in matrix metering and then in evaluative metering, if my thought is correct and the fuzzy logic has a different weighting in the two cameras metering algorithm then the two matrix metered shots will be different but the two evaluative metered exposures will be the same. But that is a complete guess and I don't have Rebel. (Unless Matrix Metering is "smart" enough to know you are shooting a gray card! Which it could be, see that is the problem with Matrix Metering...........)

« Last Edit: September 17, 2013, 01:14:37 PM by privatebydesign »
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Rienzphotoz

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Re: Why higher end camera underexposes images?
« Reply #26 on: September 17, 2013, 02:50:52 PM »
Interesting topic.
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duydaniel

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Re: Why higher end camera underexposes images?
« Reply #27 on: September 17, 2013, 03:13:33 PM »
Interesting topic.


This following video was comparing between cameras megapixels and stuff
BUT
it will answer the question indirectly (I hope)
between why pro camera slightly underexpose vs not so pro camera.

Look at the images!

Small | Large

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Re: Why higher end camera underexposes images?
« Reply #27 on: September 17, 2013, 03:13:33 PM »

Sporgon

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Re: Why higher end camera underexposes images?
« Reply #28 on: September 17, 2013, 03:15:33 PM »
It always amuses me that even with the evolved matrix metering it will still under expose a snow scene or over expose a coal hole. But I guess this is because the meter doesn't recognise the scene as white but just bright, or visa versa.

I thought Nikon had colour sensitive exposure metering, but when I last used one it did the same thing.

Metering a scene with the light falling on it is one thing, metering to include the light source is another. My guess is that the 12% vs 18% issue is something to do with pictures often having the actual light source in them - the sky. In that situation the 'correct' exposure becomes a compromise anyway.

The matrix metering does definitely differ between cameras; the 6D response differently to the 5Dmkii in matrix mode, but I think on a plain grey card they would be the same. I'll try it tomorrow.

duydaniel

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Re: Why higher end camera underexposes images?
« Reply #29 on: September 17, 2013, 03:45:12 PM »
The matrix metering does definitely differ between cameras; the 6D response differently to the 5Dmkii in matrix mode, but I think on a plain grey card they would be the same. I'll try it tomorrow.

I am not sure the 5D2 but 7D -> 5D3 have been using 63 dual layers zone
I believe the 5D2 used an older metering so we expect it to meter differently.

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Re: Why higher end camera underexposes images?
« Reply #29 on: September 17, 2013, 03:45:12 PM »