Thanks Goofy and Jumbo for going out and trying to find the answer, you have set up the discussion for why CMH bulbs are best for our babies.
Lumens has absolutely NOTHING to do with what a plant wants, it is a measurement for how humans percieve light, not plants.
It has become a pseodo measurement for MJ growers simply because it is most usually printed on the package where the specs that actually matter are not.
I will post 3 pictures the usable spectrum of the sun, the part of it that plants use and the spectrum of CMH compared to HPS, you will be able to see why I like CMH so much.
and for those of you that want to know the proper terms for research here is a quote from a regular (non-MJ) garden forum (I keep tellin you these forums are great to lurk in, they have no myths, they experiment, and they exchange honest info)
He puts it so well that quoting him was easier than me typing it out for you