I just ordered a gray card to play with in processing photos in light room 4.1. I will be taking photos at a football game both of the pom girls and the players. The stadium lighting is aimed at cener of field so the sidelines and stadium have much less light than center field. Does it matter where the picture of the gray card is taken. My photos are take from off the field in the stadium or outside the fence. The camera is in the stadium light as the subjects are in differnt light. Am I correct to assume taking the picture of the gray card should be in relation to where I am posisitioned to take the photo rather than in the light of the subject of the photo? As daylight turns to dark it would be tough to go out on the field to take a picture of a gray card. Another thought would be taking pictures in a live theater with lots of different colors of stage lights. Taking a photo from the audience would be in much less light than the light on the stage. would the gray card photo be taken in the darker area of the auditorium or in the lighted area of the stage?