It doesn't emphasize red. You're simply getting the color wheel out of balance by underexposing it and messing with blue reproduction in the shadows, shifting this toward magenta. That's perfectly fine from a creative standpoint if it is what you want and like, but you're explaining it on the wrong basis. Ektar is fairly remarkable as a color neg film because you can generally keep the neutrals in balance at the same time, much like Kodachrome of old, but not if the respective dyes are exposed askew, out of relation to one another. Because this film has higher contrast, the geometry of the sensitivity of the respective curves has to be kept parallel if you want an objective result. Also color temp correction as needed, through appropriate filters. What gives a better indication of whether or not you've mastered Ektar is when you can make a wide spectrum of hues sing in overcast light and at least pretend to be a chrome. Have fun, regardless!
