[yolk]

do you guys keep the light efficiency at the default 17%? or do you change it to 50 or 100%. do i get another result when i use a 1000 watt light source a 17% efficiency or a 170 watt source at 100% efficiency???

[jomaga]

Luminous efficacy (or efficiency) of a light source is a ratio of the visible light energy emitted ( the luminous flux) to the total power input to the lamp. So, is set to certain bulbs. Of course you can play with the value as you want. More efficiency with a fixed watts value mean more light intensity (in lumens)
A few examples with some comercial bulbs: