A 600 watt HID will illuminate a 3.5' x 3.5' garden.
A 1000 watt HID will illuminate a 4' x 4' garden.
All estimates maintain 50w per sq. ft. of light coverage.
These numbers assume you have a good reflector around your bulb and also reflective wall coverings. You can increase the figures a bit if using multiple bulbs, due to their overlapping effect. You can also increase coverage using a light mover.
Oh I know, I saw you put estimates and not fact. I have seen a ton on lumens also, everyone a little different. And also on HID distance. I'm not trying to discourage you or discredit you I was just commenting on it.
Bloodshotz is giving quality info here that is used as a standard by most HID growers who will reference "sq ft per watt" rather than lumens per watt..which tends to be a term the CFL crowd uses more than the HID crowd.
Some folks use more..some use less. In the end it's all about containing the light in a high concentration and bouncing it around sufficiently/as much as possible while keeping the space within optimal growing temperatures.
Oh yeah I agree with both of you, and I also agree that it has alot to do with reflectivity. btdt I wanna ask some questions on Lumens if you don't mind, I'll start a thread so I don't mess with Bloodshots thread anymore...sorry Bloodshot.