Grey card

brettprobert

How and when does one use a grey card? Does a grey card on a phone suffice?

bruto

A grey card is meant to exhibit the correct shade of gray (18 percent I think), which should fall exactly at the midpoint of your spectrum (or your histogram if you are reading a histogram of the exposure). If you are doing a custom white balance setting on the camera, one of the ways to do this is to take a picture of a gray card. Taking into account whatever light is present, the camera will adjust white balance to make that picture match what it sees.

I would not trust a display of a gray card because any mis-calibration of the display will change it.

You use a gray card when you want to get the most accurate tonal range possible. Whether this always corresponds with the most pleasing tonal range varies, but if you calibrate exposure to a gray card then whatever dynamic range your camera is capable of will be centered, and clipping of shadows and highlights will be minimized.

brettprobert

Okay, thank you. I'll try it out.