How do I make my Omni Light Object relate to real world lighting settings?
The Omni light object is not a precise light source, it is used for conceptual lighting scenes where real world lighting is not required.
To use a more relevant object, one should employ a Photometric Light. A Free Sphere type gives similar lighting style to an Omni, but you will need to adjust exposure settings to ideally mr Photographic exposure for best results. As well as adjusting the brightness to a realistic level.