Mesh emission strength to Area lamp strength I've three emissive mesh planes in my scene which I'd like to convert to Area lamps.

I've set my new Area lamps to use precisely the same size, location and strength as the planes were. But when I press shift+Z to preview the render, lighting is much, much darker than it was with the planes.

Is it just matter of me bumping up those Area lamp strengths, or is there something more to consider, if my goal is to get identical lighting what I had before with the planes?

Also is there some kind of formula I should use to convert emissive plane strength to Area lamp strength, or should I just eyeball it?
Yeah that was a problem I had, I did some testing and found that its something like 15 to 1 ratio.
If I had a Plane with the emission strength 1 then I needed strength 15 for the lamp.