Light distance chart

[LabMan]

Hello everyone,

I remember seeing a chart someone posted to a journal I was reading a while back showing the proper distance in inches away from the plant for certain wattages with CFL, HID, and LED. Does anyone know where I might find that. I can't for the life of me remember which journal I saw it in.

 

[LEDBud]

I have only seen charts that show the lumen strength reduction at different heights from the plants.

So I had a look to see if I could find the chart you were looking for

Link to a 420 thread , scroll down a few posts
What distance should my light be from my plants?

Although the chart is for HPS bulbs , the thread may cover other bulbs.

 

[LabMan]

Thanks LEDBud! This is what I was looking for. I see the chart is labeled HPS. Do you think the distances would differ for LED if I am going by wattage?

 

[LEDBud]

The closest distances might be to close for the LED's and the further distances to far away.. I would not put them 6 inches from the top of the plant. (after my trial and error)
10 inches to 1ft should be your closest light distance with LED's , as I bleached and damaged the new growth on the top of the plants at 6 inches ( with young plants )

Also at 1ft a 300w LED panel has about a 2ft spread (more for higher watt panels), at 2 feet you would get more like a 3 ft spread but it would reduce the lumen the plants received by about 50% compared to 1 foot.

The Lumen loss by distance is incurred by the LED's and HPS at approximately at the same rate.

Given that I assume the chart is *almost* a direct fit to LED's.


I would never hang a light 30" from the plants either , I like to pound them with light rather then trickle them with light..

I will suggest 2ft to be your height with the Larger 900w panels and 1 foot with the smaller 300w panels.

You can lower the LED panels until you see bleaching or leaf curling or dead spots , then you know your to close and should raise them 6 inches. Its better to start to close and raise them then to start to far away and leave them IMO.

 

[Graytail]

CFL doesn't really matter, and LED is mostly a coverage issue.

 

[LabMan]

Thanks for all the helpful info and link LEDBud, and for the PAR chart Graytait. I have a science background and feel a little more comfortable if I can see some data to go along with people's experience. So this helps clarify some questions for me.

 

[Techhead]

with LEDs you need a little distance so all the LEDs can blend there colors. The inverse square law is in effect for all lighting, but if you are running a led panel with lenses, the inverse square law kind of goes to hell depending on how sharp of an angle the lenses are, and some extra head room is needed for the lights to blend. I am keeping my lights up about 1 foot plus a few inches. But then I'm running mostly 5 watters, and 45degree lenses, (30 degree on the 3 watt deep reds to really drive them home). So there you go, more info to get really confused, sorry

 

[LabMan]

hahaha, No I appreciate all the info I can get, Thanks.