Pictures full credit goes to cine4home.
There are three things what influence the brightness of the picture:
The power of the lamp, the position of the iris and the cine filter who is not engaged in the first two modes vivid and living room.
Let´s meet the iris and the cine filter.
When you switch from vivid or living room to the other modes the cine filter moves into the light path.
|iris off and in open position - cine filter disengaged|
|iris on and in closed position - cine filter disengaged|
|iris off and in open position - cine filter engaged|
How much lumen do the modes provide in Normal and Eco
Vivid: iris off 1800/1335 - iris on 1220/940
Living Room: iris off 1500/1100 - iris on 960/760
Natural: iris off 640/510 - iris on 430/360
Cinema: iris off 550/470 - iris on 380/300
To bring more light but a better color space Epson came up with an old idea I had on the first Sony HD projector the VPL-HS10 already years ago.
They call it Light Power and you put a color filter in front of the lens.
With this you do not loose so much light and you get:
Light Power: iris off 1300/940 - iris on 870/670more detail here