How do I use the ExpoDisc with a flash unit?
Removable flash units, or bounce (reflected) flash will provide the best results when setting a white balance with the ExpoDisc. When using removable flash units to light a subject, position the flash then aim the camera back towards your main light (flash) from subject position. Be sure to trigger the flash while taking your custom white balance capture. When using bounce flash, aim the camera and flash towards a neutral surface (e.g., white ceiling, gray pavement, etc.) for your custom white balance capture. Non-neutral bounce surfaces may introduce a colorcast if used to reflect a flash for the purpose of setting a custom white balance. Avoid aiming the camera and flash towards a backlit subject. A subject backlit by light that is either warmer or cooler than the light illuminating them from the front will produce an incorrect white balance.
