is 80,000 foot candle at 10 inches away from 1000watt a good reading???

[brotherlewrl]

im worried that my lights are not as bright as they should be. i bought a foot candle reader and took some measurements. at 10inches 80,000 at 15 inches 52,000 and 18 is 47,000 foot candles. are these decent readings, xtrasun 1000watt hoods with glass. if anyone has any info that would be awesome!

 

[kingtut]

it's all about the lumens man. for example, there is an equation which goes L=1/dsquared. d is the distance from the plant in feet (squared) divided by one. So, if your plants are 1 foot away from your 1000, you should get the maximum lumen output (around 100,000) for that bulb. iunno what the candle feet shit is, but all you need to care about is lumens lumens lumens. I know people who have yielded less on 1000w than my 400w because they just shearly don't understand what they are doing. It's all about playing God and being able to control your light movements, air temps, and nutrient feeding schedule. I hope this helps! LUMENS!

 

[Papa]

brotherlewrl,

no, that is not an accurate reading. my first thought was that you're reading lux and not footcandles . . . and that would be closer to the numbers you have . . . but also seems a little off [but maybe not] depending on the efficiency of the xtrasun reflector, the efficiency of the ballast, and the cleanliness of the glass on your fixture. 1 Lux (lx) = 1 Footcandle (fc) x 10.76

direct sunlight in the middle of a summer day is about 10,000 footcandles.

bare lamp footcandles for 1000w HPS as measured recently by Bossman were:

1000 watt HPS magnetic ballasb.
2 ft away 4200 fc
3 ft away 2700 fc

1000 watt HPS digital Global Green house
2 ft away 6630 fc
3 ft away 5000 fc

1000 watt HPS digital Future Bright
2 ft away 5500 fc
3 ft away 3200 fc

as for that other post [rolls eyes] where do i start? :sign0065:

"iunno what the candle feet shit is" . . . then WHY the :sign0055: are you posting????

Lumens are the unit of measurement used to quantify the total amount of visible light emitted by a source. For a floodlight source like a 1,000w HPS, that's the total amount of light emitted in ALL directions.

Footcandles and lux are units of measurement to quantify the amount of light at a specific point.

"L=1/dsquared. d is the distance from the plant in feet (squared) divided by one. So, if your plants are 1 foot away from your 1000, you should get the maximum lumen output (around 100,000) for that bulb."

that equation and sentence makes absolutely no sense WHATSOEVER!!

perchance the equation that he is attempting to reference [or at least the closest reference I can think of] is:
fc = I ÷ D2
where fc=footcandles, and I=Candlepower in candelas, and D=distance from light source.
but candlepower is a unit of measurement of a lamp [or fixture] that directs the light in a controlled manner and there are HPS fixtures that have had photometrics done to give us the candlepower numbers . . . but these are typically fixtures like stadium and parking lot lights and not growlights . . . so this equation doesn't work for us anyway.










Papa

 

[joonie]

So is 2200 fc for a 1000w hps bad? The meter I have is reading 22.3 x100.

 

[shawnskush]

:banghead: