HalfSize

All camera slates in half size, which is equivalent to A5. As a rule of thumb for full frame clapping the distance between camera and slate corresponds to the focal length of the lens in cm - for a 50mm prime it's ca. 50cm. Thats only valid for S35 sensor sizes (Arri Alexa, Amira, etc.). You have to calulate a crop factor for all other sensor sizes.