48'' away from baby plants but not recommended until good roots are formed. Flip into bloom when plants are @ 24" tall and move light down 12" if still at 48". This is the company's info here guys.. So, I guess they are saying 12" to 18" away from tops.. But you'll have to fine tune.. Depending of course.. they are pricey and I have no results as of yet to share but, I figured I'd share the knowledge for those who needed it.. as i once did
as far as i know, we always recommend 24-30 inches for germination and 18-24 inches for veg, 12-18inches for flower. but some growers also go with their own ways and also doing very well.