Light to plant distance charts / How far should the light be

good reference my friend

 

When using HID lamps, the struggle is always placing bulbs as close as possible without the negative effects of heat. According to this chart I can place HPS lamps a couple of inches away, which doesn't seem right to me. It might be the best use of the lumens but if it's gonna boil the plant then what?

 

The chart isnt a measure of heat, and its funny I only found out not to long ago what a foot-candle really is. Basically the amount of light that actually falls on a given surface. A foot-candle is equal to one lumen per square foot.

So with cool tubes if could get within 4" which is not recommended, the range would be 315,000 ft/candles. Insane, wouldnt that bleach em out?

 

A foot-candle is the illumination on the inside surface of a 1 foot-radius sphere where 1 candle is the light source sitting exactly in the center of the sphere.

Also, 315000 lm/f2 is a sick value [5000lm/f2 is the sun]; how did you get that?

Also, intensity of artificial lighting decreases at the rate of 1/2 per each foot.

EDIT: I forgot the foot-candle

 

Thats exactly what wiki says..... I was just using lei mans terms. the 315000 is from the chart for MH at 4 inches.

 

well, ofc, wiki wasn't going to publish wrong info

I gotcha

 

so confused what the hell you guys talking about.

Flouros FTW

 

Excellent thread. I was wondering if you had one for CFL lights as quite a few people (including myself) are going for this option.

In my case I have 9 18W energy saving lamps that are supposed to generate an equivalent output of 120W each, giving 1080 (ish) in total and I am about to install a further 5 giving another 600W on a side wall.

Also, and sorry if i am highjacking this thread, but while on the subject of CFL I found some t5 plant pro lights from:

http://www.arcadia-uk.info/product.php?pid=34&mid=10&id=4&lan=en

At the bottom of the link it includes the light spectrum for it.

Any thoughts from all you mighty wise stoners?

 

Spectrum for the T5 Plant Pro.

Just thought it would be easier posting it rather than opening a new window.

 

When using CFLs, forget about the incandecent equivalent power, doesn't mean much to us. I don't know much about T5 (or any floro tubes) but if you're gonna use CFLs, try to get bulbs 23W and above, low Watt bulbs are not very efficient for growing.

 

The charts dont reflect the distance if youre using a 1000w with a blower attached to the light housing correct?

 

Still a newb as far as the 'gardening' goes, but if you were thinking about '54 watt high output T5's, which generate 2100 lumens, consider a 200w-equivalent 45watt CFL instead, which consumes only 45 watts and generates 3000 lumens in a much tighter space, with a much cheaper fixture. Cool white bulbs of this type are only $16-- at my local building supply megacentre, and 19-- at W4l-M4rt

My seedlings and clones love it, tho the MH beats it for sheer power One /could/ postulate a very tight grow in a closet using only (a whack o') these, and prolly get decent results If one were to factor in lumens/watt, tho, the 100w equivalent / 23w CFL are actually a whisker more efficient.

Just my 2c