Exposing RAW images is a litte different than exposing images on a video camera. Here’s why: with video cameras, things like white balance, asa/iso, the colour curve (knee/toe and/or picture style) and gain settings are “baked into the image”. In other words, these factors–all of which manipulate the image–are inextricably applied to the actual image that the sensor receives through the lens.
With a camera that records the RAW image that the sensor receives, these factors (called metadata) are applied in a separate process (called transcoding). The HUGE advantage here is that cinematographers are able to finesse those factors (especially the curves!) with far more control in post than they would ever be able to achieve on set.
The thing is, anyone that has exposed with a waveform and calibrated monitor is used to relying upon an image with metadata already applied to it (that’s what the video cameras were all producing until RAW motion capture), which can lead to poor exposure with RAW cameras.
Here’s an educational piece from RED that can help you expose Epic correctly: Exposing RAW