how to measure light

[fiddyonefiddy]

yes you got it another noob(also know as stumps where i come from) question.
i have a light meter but it is only rated in candle power
anyone have a formula for converting this so i can kinda get an idea of how much more light i need
im using a 125 w hps light now for veg.
just wondering if someone had a link to something that could help out.
thanks in advance!
speedy

fiddyonefiddy Reviewed by fiddyonefiddy on 02-19-2008. how to measure light yes you got it another noob(also know as stumps where i come from) question. i have a light meter but it is only rated in candle power anyone have a formula for converting this so i can kinda get an idea of how much more light i need im using a 125 w hps light now for veg. just wondering if someone had a link to something that could help out. thanks in advance! speedy Rating: 5

[melodious fellow]

you are straight brotha...

with a 150 watt hps, you can provide enough light for 4-6 plants to veg. Maybe 10 plants if you SOG/SCROG (plants kept very close, stay short (screen) and flower early. Less yield per plant, but more plants)

Anyway, good luck and don't fret about light with anything HPS lol

[fiddyonefiddy]

just using the 150 for veg then going to 400w hps for flower
i have 6 plants total. thanks again melodious

[melodious fellow]

I actually saw a photometer the other day, first time I had seen one.

It was a two or 3 in one, Ph, mositure, photometer, I dunno, one of those crap meters that I have wasted so much $ on...

It did not measure in Lumens however, I do not believe. It went from 0 to 2,000 or something like that, likely candle power like yours, yeah?

By the way, midday, summer sun is around 10,000 lumens per square foot.

You HPS can match that or even top it if your grow area is compact enough.

Peace dawg and keep us updated on yo grow... *coughs* grow log! *coughs*

[OLDJIMMYBONES]

im guessing you want it in lux?


Lux versus footcandle
One footcandle ≈ 10.764 lux. The footcandle (or lumen per square foot) is a non-SI unit of illuminance. Like the BTU, it is obsolete but it is still in fairly common use in the United States, particularly in construction-related engineering and in building codes. Because lux and footcandles are different units of the same quantity, it is perfectly valid to convert footcandles to lux and vice versa.

The name "footcandle" conveys "the illuminance cast on a surface by a one-candela source one foot away." As natural as this sounds, this style of name is now frowned upon, because the dimensional formula for the unit is not foot · candela, but lumen/sq ft. Some sources do however note that the "lux" can be thought of as a "metre-candle" (i.e. the illuminance cast on a surface by a one-candela source one meter away). A source that is farther away provides less illumination than one that is close, so one lux is less illuminance than one footcandle. Since illuminance follows the inverse-square law, and since one foot = 0.3048 m, one lux = 0.30482 footcandle ≈ 1/10.764 footcandle.

In practical applications, as when measuring room illumination, it is very difficult to measure illuminance more accurately than ±10%, and for many purposes it is quite sufficient to think of one footcandle as about ten lux.

[fiddyonefiddy]

ahhh thank you gents

yes mine has three switches goes up to 1000cp then has a screen filter that you X10 of the scale. right now without filter im burying the scale.

[melodious fellow]

[quote=OLDJIMMYBONES]im guessing you want it in lux?


Lux versus footcandle
One footcandle ≈ 10.764 lux. The footcandle (or lumen per square foot) is a non-SI unit of illuminance. Like the BTU, it is obsolete but it is still in fairly common use in the United States, particularly in construction-related engineering and in building codes.
/QUOTE]

Light bulb packages in the US read in lumens, as do bulb sites 1000bulbs.com and hydro shops equipment, most of the lighting guides on here, etc., yeah?

Actually, come to think about it, just about any time I see any measure of light relating to cannabis it is in lumens...

[OLDJIMMYBONES]

[quote=melodious fellow]

im guessing you want it in lux?


Lux versus footcandle
One footcandle ≈ 10.764 lux. The footcandle (or lumen per square foot) is a non-SI unit of illuminance. Like the BTU, it is obsolete but it is still in fairly common use in the United States, particularly in construction-related engineering and in building codes.
/QUOTE]

Light bulb packages in the US read in lumens, as do bulb sites 1000bulbs.com and hydro shops equipment, most of the lighting guides on here, etc., yeah?

Actually, come to think about it, just about any time I see any measure of light relating to cannabis it is in lumens...

i kno. i live in the us, but lumins are a mesure of light in a square foot or meter and you cant convert a foot candle into a lumen
+ you wont find an accurite light tester that shows lumens (but of shit ones that do),

bc

The footcandle (or lumen per square foot) is a non-SI unit of illuminance