This tip is so easy I am sure some of you out there will kick yourself when you finish reading. Like you, I still learn things and this tip was passed to me a year ago…after 20 years of shooting without it. Photography is a journey, not a destination. Don’t’ sweat when you learn something, just be happy you’re smarter because of it.
A gray card is a card that is 18% gray. Why this is important is because your camera assumes the world is, on average, 18% gray. And it’s right, part of the time. This is the main reason scenes are not exposed as you would like when using P or A or S mode; because your camera is programmed to assume the scene in front of it is 18% gray and it wasn’t 18% gray. To demonstrate this on your own, set your camera to P mode (gasp!) and take a picture of a white piece of paper. Now set your exposure compensation to +1 or +2 and take the same shot. Which one looks more like the white piece of paper?
The overexposed one. Because the piece of paper is not gray, but your camera tried to make it that way.
Enter the gray card! To use a gray card, hold it up in the light that is the same as the light hitting your subject, point your camera at it (preferably using spot metering mode for best results) and you now have a ‘perfect’ setting. This 18% gray card is what your camera assumes the world is; placing such a card in front of your camera now makes it able to meter the light with better accuracy. Perfect exposures. Or at least a great place to start.
Just like eating enough fiber or getting enough sleep, you know using a gray card is good for you(r photography) but you don’t do it all the time. I don’t do it all the time either. Why? My number one reason is the card is not always with me. A dedicated shoot I am being paid for? Of course it is there. But taking my daughter to school and seeing something worth shooting on the way? It’s not with me 100% of the time (also because I test many camera bags and it doesn’t always get packed into the right bag). Plus, who has time to pull out the card when the lighting is just right and the card is in your bag in the car? I’m as good at making excuses as the next guy.
Now what if I told you you could have a gray card with you all the time?
That’s right, as long as you have two hands, your gray card can always be with you.
The technique is simple and the idea is that the color and tone of the palm of your hand doesn’t change much. Certainly not as much as that back of your hand which has more pigment and sees more sun. Why not use that?
To use your hand as a gray card you will first need a gray card. They are cheap and you can order them online or find them at a local photo shop. In a nice even light, using spot metering and manual exposure mode, point your camera at the gray card. Set your ISO so it is not on Auto and maybe to 800, the number isn’t too important. Now adjust aperture and shutter speed until the camera metering is at zero, meaning it is not over or underexposed according to the camera. Next place your hand (I suggest your left hand) where the card was, with your fingers together. Ensure the center metering spot is completely covered by your hand.
What does the camera’s meter read now? Mine says the settings I had for the gray card are 2/3rds of a stop too dark for my hand. It thinks these settings will make my hand too dark, but not so, because we set the camera’s settings using the gray card, which is accurate and matches the camera’s metering expectations. This means whenever I point the spot metering at my hand, and my hand is in the light hitting my subject, I just have to adjust my settings until my camera thinks the exposure is 2/3rds of a stop too dark and I am set!