Feedback Please: The Kodak 18% Grey Card and Metering, a new look.

[BrianShaw]

The questions for me (and I think know the answers already) ar:

If I point my reflected meter at a scene will it give me a good enough exposure recommendation or do I need to alter what the meter suggests?

If I take an incident meter reading...

If I take a reflected meter reading of a gray card...

What's the difference between a gray card and a grey card?

 

[Bill Burk]

I do not agree with RobC's 8% solution, but I do have a possible explanation how he might be seeing dark gray Zone V results in his prints...

RobC aims to develop his negatives (I think it's a fair estimate based on his discussions) to N-1, while I aim to develop mine to Zone System N Normal.

0.48 CI is a fair representation of RobC's aim negative (left), and 0.57 CI is close to mine (right).

When I made these Zone Rulers, I made a good faith effort to print scales useful for visualizing the print results that you would get for different Zone placements for N-1 and N Normal.

Notice how dark the N-1 patch for Zone V is (about 6% gray) and how N Normal Zone V is a middle gray (about 18% gray).

So it will work to assume the meter reading will print as 8% gray on the print... if you develop to N-1.

This is where my generic advice applies: If you want to follow someone's teachings, follow them all the way. Sometimes their assumptions contain errors but still work in practice... not necessarily because they are right, but because they are consistent.

 

[RobC]

If any beginner was/is trying to get a grip on what an 18% grey card is they are sure gonna be hellish confused by now. Oh well, I tried but the usual suspects wouldn't let it happen as usual.

And bill, I think you are a bit off with my calibration as zone X is pure white for me and IX just a hint of tone. BUt yes I get what you are saying and am fully aware of it which is why I have pointed out that there is NO STANDARD for middle grey as a negative density. But for colour work there is also very little room for manouvre which there is in B&W. So its more complex than even you have shown. Technically speaking we really should be using an incident meter if we want consistency in colour reproduction becasue its pretty difficult to get it consistently spot on with a reflection meter unless you have done very careful and full calibration through to print which most people never do. And if you are using an incident meter yo can throw the grey card out or just use it as a neutral colour reference for the printer to adjust colour pack to.

 

[markbarendt]

This is where my generic advice applies: If you want to follow someone's teachings, follow them all the way. Sometimes their assumptions contain errors but still work in practice... not necessarily because they are right, but because they are consistent.

Absolutely.

I see this in many disciplines not just photography.

Everything works well for them until an abnormal situation trips them up. It's not that the rules of the universe changed its that the special case they were operating in changed.

 

[RobC]

And bill, my 8% was not targetted to any colour in the print. It is a factual consequence of using a K Factor = 12.5 and targets the middle of a film curve of 7 1/3 stops exposure range and not middle of a colour range. It could be any colour or reflectance you like in the print. I don't care unless I'm looking for colour reproduction accuracy which I'm not when doing black and white.
So as for your explanation, you must ensure you have understood what is being said otherwise you are likely to come up with an interpretation which is complete bollocks.

 

[Stephen Benskin]

It is a factual consequence of using a K Factor = 12.5 and targets the middle of a film curve of 7 1/3 stops exposure range and not middle of a colour range.

And where exactly is this middle of the curve found?

 

[markbarendt]

And where exactly is this middle of the curve found?

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