The ExpoImaging ExpoDisc 4 x 5.65" Video Format Filter - Neutral
solves the problem of color balancing difficult video shooting scenarios. With this accessory, you will not have to carry additional cards and targets with you to balance your light. Consisting of multiple layers of carefully selected materials, the ExpoDisc is guaranteed to be within +/- 2% of neutral for demanding professionals.
The ExpoDisc acts just like an 18% gray card when used to measure the incident light, and, as such, can be used instead. The sophisticated design enables the ExpoDisc to receive, scramble and passively transmit mixed light from a wide angle in front of the disc through to the image sensor for a more accurate and efficient white balance correction.