My understanding of the measurement of lumens is that a lumen is how much light the source gives off to a point that is one foot away. So 53,000 lumens would be the amount of light a plant gets when the light source is one foot away. So if the source is two feet away, then the plant only gets 1/2 that amount or 26,500 lumens.

Conversely, bringing the light closer, say 2 in. away from the top of the plant, would increase the amount of lumens the plant receives. Can someone confirm/refute this as I'm not entirely positive of the latter portion of this post?