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  #11  
Old 25th November 2014, 01:28 PM
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You should use white i.e. paper base as your 0 stop reference; "black" will be dependent on the maximum density (Dmax) of the paper. Matt papers have a lower Dmax than gloss. The only way to be certain your grey card is the correct density is to use a densitometer to measure its reflection density which should be around 0.74 according to Kodak.

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I have never understood the use of a grey card when one can actually meter the scene.
That's true if it's an average scene but if it's a black cat on a dark rug or a fried egg on a white plate you can run into trouble; a grey card is very useful in such circumstances!
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Old 25th November 2014, 02:13 PM
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You should use white i.e. paper base as your 0 stop reference; "black" will be dependent on the maximum density (Dmax) of the paper. Matt papers have a lower Dmax than gloss. The only way to be certain your grey card is the correct density is to use a densitometer to measure its reflection density which should be around 0.74 according to Kodak.



That's true if it's an average scene but if it's a black cat on a dark rug or a fried egg on a white plate you can run into trouble; a grey card is very useful in such circumstances!
If you are using an incident meter then you should metering the light and not the cat or egg and if you are using a spot meter then you meter the dark rug and place it on zone 2 to 4 depending on how dark it is or meter the white plate and place it on zone 8 or 9. I fail to see why a grey card is required.

Last edited by Argentum; 25th November 2014 at 02:38 PM.
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  #13  
Old 25th November 2014, 02:35 PM
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It's not required, but it can be useful.
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Old 25th November 2014, 04:57 PM
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Quote:
Originally Posted by Argentum View Post
If you are using an incident meter then you should metering the light and not the cat or egg and if you are using a spot meter then you meter the dark rug and place it on zone 2 to 4 depending on how dark it is or meter the white plate and place it on zone 8 or 9. I fail to see why a grey card is required.
Quite, but if someone wants to use one then fine by me but they should be aware that, for example the card that Kodak used to sell, any sheen will vary the reflectance of the grey card whereas, if you meter the dark shadow that you wish to retain detail in and place it on Zone III you are fixing an actual point on the exposure scale for the actual scene.

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Old 25th November 2014, 06:23 PM
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It's worse than that, the angle of the card to the primary light source and the camera have to be exactly to the defined angles as detailed in the usage instructions otherwise it doesn't reflect 18% to the meter. You would need a sextant to set it correctly. And then as discussed in another thread, it doesn't represent the middle of anything except a 5 stop range and will usually result in under exposure when using black and white film unless you've calibrated your exposure and development to a grey card.
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  #16  
Old 27th November 2014, 01:54 AM
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Originally Posted by Argentum View Post
And then as discussed in another thread, it doesn't represent the middle of anything except a 5 stop range and will usually result in under exposure when using black and white film unless you've calibrated your exposure and development to a grey card.
Can you direct me to this thread. I don't understand why a change in the brightness range of a scene will change the midpoint of Zone 5
Thanks
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Old 27th November 2014, 08:18 AM
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Can you direct me to this thread. I don't understand why a change in the brightness range of a scene will change the midpoint of Zone 5
Thanks
http://www.film-and-darkroom-user.or...7&postcount=31
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  #18  
Old 27th November 2014, 04:19 PM
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Thanks!
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  #19  
Old 28th November 2014, 11:37 AM
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I have never understood the use of a grey card when one can actually meter the scene.
Or meter a white card (which will be more accurate even if not 100%) and compensate.


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  #20  
Old 28th November 2014, 01:23 PM
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Thanks!
Just updated that topic

http://www.film-and-darkroom-user.or...2&postcount=54
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