Using Grey Cards
 

I have never used Grey cards and I was wondering what the importance of using grey cards for setting up your white balance is.

Do you guys use it very much with your cameras?

Thanks

It just changes the color temperature of the picture.

Actually if you're interested in changing the color temp on your video using white balance, I would check out www.warmcards.com.

I got a set of these and they actually work really nicely.

There’s a card for indoor, outdoor and fluorescent lights. It really helps with color consistency if you're moving from interiors to exteriors a lot.

I've never thought/heard of using a grey card for white balancing a camera... I've used them as a reference for colour correction in post for exposure and gamma. Especially useful when using two different cameras that may have slightly different gammas. Although a greyscale chip chart would be even better for this than a single grey card.

What is the difference between a grey card and warm cards?

A gray card is neutral. A warm card is slightly blue in color and tricks the camera into balancing warmer. I use a Gretag digital grayscale for white balancing, and as a reference for post. It is only a black, white, and middle gray reference, but I find results in more consistently accurate white balancing and makes a good reference for color grading.

Sean has it right.

In my opinion, if i can buy a bunch of laminated cards for $50 that makes a noticable difference in my video ... it's well worth the cost.

I like the Warm Cards because they make everything pop and they're super easy to use.

It's been my experience that good video does not necessarily come from a good camera and that accessories (like matte boxes and filters) can make a huge difference in the quality of your final product.

An 18% grey card is used for metering on set (using a spot meter) in order to set exposure.

Shooting a grey card (along with a Macbeth chart or similar) will let you know what is white, black and 18% grey when you go to color correct.

Thanks for all the info guys!

The PP modes on the EX1 allow you to accomplish the same function as the warm or cool cards by using the WB shift function to force the camera warmer or cooler by a set amount. Ben's right, the original reason for the gray card is a calibrated value to read from with a reflective light meter, as well as analyzing exposure on film. A true gray card will reflect exactly 18% of the light that hits it. In the video world, meters are used VERY infrequently, so a gray card isn't really necessary. I have found however that I get much better results white balancing to the 3 step macbeth than to even a pure "White Balance" card.

-Sean