Middle Grey? Really?

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So lately I have been doing some snooping around to see how my camera, meter and RAW processor interact, and I found some interesting things:

First of all, my light meter does not reflect middle grey in RGB. When null, the meter records something like 28% greyscale, rather than referencing at 50% when using the default parameters in Raw Photo Processor.

I can adjust this using a "brightness" parameter, which functions similarly to Gamma, but in the "film" curve type in RPP, and now have my meter nulled out to 50% greyscale. This places -5ev/Zone 0 at 7% greyscale and +3.6ev/Zone VIII+2/3 at 95% greyscale.

But I am curious what exactly is causing this. Is the meter off - or is it something in the curve? I read something about 12% and 18% meters in RPP's manual, and that you can somehow switch between the two - but I thought this was more about the zone system UI.

At any rate, when you process middle grey, does it come out to 50%, or some other value?
 
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So, middle gray/ 10-18% reflectance, what your cameras light meter aims for, is not accurate on your camera?!?
 
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... i think it's a bit more likely that it has something to do with the processor than the camera.
 

ann

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Interesting,

To be honest I haven't paid that much attention to a specific number, I have noticed that when i get a new camera body i have to test to compute the meter to my brain (so to speak) and it always varies.

With film , I would test and read the densities for specifics and then determine my EI for each camera or lens.

Perhaps this weekend, i will run some "number " test with my d700 and see what comes up.
 

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The traditional 18% grey standard for reflectance metering is no longer universal. I'm not sure about the other major players, but I know that Nikon does not use it; A number of years ago, when I was working with my first digital SLR, I was doing some shots where exposure was absolutely critical. Being 'old-school', I whipped out my Luna-brick and grey card and double-checked the exposure against the camera. It was consistently about 2/3 of a stop out. Concerned that I had an issue with my camera, I called Nikon Canada, and through sheer luck, wound up talking to someone fairly high up in repair/warranty division. He assured me that there was nothing wrong with my camera, and while he wouldn't allude to what standard they had chosen, or whether it was the same for all of Nikon's bodies, he did very clearly indicate that it was NOT our old friend 18% grey.
 

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Out of curiosity, what made you look into that? Are you having white balance issues?
 
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I am working on an unified exposure method for digital that takes into account shadow compensation, similar to the zone system - but in reverse. You'd expose for the hilights and process for the shadows.
 

ann

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The traditional 18% grey standard for reflectance metering is no longer universal. I'm not sure about the other major players, but I know that Nikon does not use it; A number of years ago, when I was working with my first digital SLR, I was doing some shots where exposure was absolutely critical. Being 'old-school', I whipped out my Luna-brick and grey card and double-checked the exposure against the camera. It was consistently about 2/3 of a stop out. Concerned that I had an issue with my camera, I called Nikon Canada, and through sheer luck, wound up talking to someone fairly high up in repair/warranty division. He assured me that there was nothing wrong with my camera, and while he wouldn't allude to what standard they had chosen, or whether it was the same for all of Nikon's bodies, he did very clearly indicate that it was NOT our old friend 18% grey.


All this secret keeping is madding, do you have thoughts on what it might be? Not that i am unhappy with my results, but since i am a traditional educated Zonie, it would be interesting to know.
 
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ann - the more you dig around with digital, the less you wish you knew.
 

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Using the default settings on my D3 and the internal meter, it produces an image that is 120, 120, 120 - ie L = 51 and B = 47%. Now you could argue that L should be 50, which is 118, 118, 118. That is what my old Leica Digilux 2 produced.
 
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^^ you get what you pay for I guess :)

I need to d/l the Sony image processor software anyway. I wonder if it will make any difference.
 

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The traditional 18% grey standard for reflectance metering is no longer universal. I'm not sure about the other major players, but I know that Nikon does not use it; A number of years ago, when I was working with my first digital SLR, I was doing some shots where exposure was absolutely critical. Being 'old-school', I whipped out my Luna-brick and grey card and double-checked the exposure against the camera. It was consistently about 2/3 of a stop out. Concerned that I had an issue with my camera, I called Nikon Canada, and through sheer luck, wound up talking to someone fairly high up in repair/warranty division. He assured me that there was nothing wrong with my camera, and while he wouldn't allude to what standard they had chosen, or whether it was the same for all of Nikon's bodies, he did very clearly indicate that it was NOT our old friend 18% grey.


All this secret keeping is madding, do you have thoughts on what it might be? Not that i am unhappy with my results, but since i am a traditional educated Zonie, it would be interesting to know.

I thought Thom Hogan's tests (a few years back) said Nikon was aiming at 12.5%. That's the last figure I heard.
 

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Some where in the outer recesses of my brain i was thinking 13%.;) then i am thinking do i care :sexywink:
 
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^^ you too do care!

once a zonie, always a zonie! :hug::
 
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The traditional 18% grey standard for reflectance metering is no longer universal. I'm not sure about the other major players, but I know that Nikon does not use it; A number of years ago, when I was working with my first digital SLR, I was doing some shots where exposure was absolutely critical. Being 'old-school', I whipped out my Luna-brick and grey card and double-checked the exposure against the camera. It was consistently about 2/3 of a stop out. Concerned that I had an issue with my camera, I called Nikon Canada, and through sheer luck, wound up talking to someone fairly high up in repair/warranty division. He assured me that there was nothing wrong with my camera, and while he wouldn't allude to what standard they had chosen, or whether it was the same for all of Nikon's bodies, he did very clearly indicate that it was NOT our old friend 18% grey.


All this secret keeping is madding, do you have thoughts on what it might be? Not that i am unhappy with my results, but since i am a traditional educated Zonie, it would be interesting to know.

I thought Thom Hogan's tests (a few years back) said Nikon was aiming at 12.5%. That's the last figure I heard.

Of course 18%, 12%, 21.3% or whatever has absolutely no importance if you have no idea what that means in your raw files/negatives. Improperly processed, metering at 18% could literally mean anything density-wise.
 

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