Your Camera's Meter Will Lie to You.....

[JacaRanda]

12%? DARN, now I have to break my New Years Resolution and continue buying $%^&&**%$%##stuff.

 

[Helen B]

12%? DARN, now I have to break my New Years Resolution and continue buying $%^&&**%$%##stuff.

The exact value isn't all that important - it's just a known reference. You can just as easily use the palm of your hand and adjust a little. You camera's meter may not really be 'calibrated' to 12% anyway. It's up to you to find where your grey/white reference falls within the dynamic range of your camera, for whichever mode you shoot in because that changes things.

 

[unpopular]

^^^^^^ THIS ^^^^^^

Helen wins the internet!!!

 

[unpopular]

You also don't need to find an exact reference, only have a rough idea of how many stops over or under the reference you choose is from the calibrated reference, and compensate accordingly.

 

[TCampbell]

If your camera is calibrated to 18% and you take a shot of an 18% gray card then the histogram is a flat line with a "spike" at the midpoint. If your camera is calibrated to 12% and you use an 18% gray card then the spike wont be in the middle (but it would be if you used a 12% card.)

I mostly use the gray card for white balance and if I really care about perfect metering, I use my incident meter ... not my gray card (and my own gray card is an 18% card even though my camera is calibrated to 12%). But if you DO use a gray card, and you use an 18% gray card with a 12% calibrated camera, just know that the histogram spike will be a little to the left of center.

 

[unpopular]

I'm not sure how much exposure would be needed to compensate a 12% meter for an 18% grey card, if it's one stop or one third stop. But you can use an 18% greycard with a 12% meter, it's just a matter of increasing exposure accordingly.