Measuring light output

[pipeman]

Typically lights are quantified in watts, but is this really an accurate measure? Watts only refers to the amount of power used, not amount of light given. For example an 18W compact fluro will give about the same amount of light as a 60W incandescent.

[Tom]

The correct way to measure light output is in Lumens (Lm) eg: the day light CF's that I use around the house (helps offset the cost of running the Son-T's) are rated at 20w, are equal to a 100w incandescent and have an output of 1,100Lm. This is the point where a few newbies get into trouble, whilst that light is putting out 1,100Lm much of it is in the wrong spectrum for growing, the warm white and cool white CF's with their lower output have more Lumens within the correct spectrum and are therefore more effective. The same applies to HID's and other forms of lighting.

 

The reason that a 20w CF can put out as much light as a 100w incandescent is that much of the incandescent's power consumption is wasted in the production of heat to make the element glow almost white hot.

 

[pipeman]

thats what I was thinking Tom, so my issue is I'm trying to design a mother room and veg room. Flower is easy at about 50+watts of HPS per square foot. However with veg and mother I'm trying to weigh up flouros to MH and not sure how to do it. I'm guessing that 100W of MH light is a lot more effective than 100W of fluro, but by how much?

 

So far in my web surfing I haven't come across data that allows you to compare the different types of lighting.

[Tom]

The Lumen output of the MH superior to the fluoro and would give you shorter node spacing and faster growth than the flouro.

 

[Jim]

is there any formula or any way of working out the quantity of Lumen's in a light ?

if anyone would like to clear that up for me.

 

tah

jim

[Tom]

The easiest way to find the amount of usable spectrum is to check the manufacturer’s web sites.

[boulder]

Try here: http://www.theledlight.com/lumens.html

 

A light meter costs about $80. Handy piece of equipment to show how short the life span of lamp really is and when to change lamps.

[boe~pimp]

just thought i would add my two cents:

 

i just checked out the sunmaster home page (checking luminary output for my sunmaster 'super deluxe hps') and thought this would fit into this topic:

 

PAR WATTS FOR PLANTS...

LUMENS FOR PEOPLE.

 

At Sunmaster, we believe there is a better way to measure artificial light: Photosynthetically Active Radiation(PAR) watts. While lumens are based on the eye sensitivity curve of human beings, PAR watts objectively measure the total watts of light emitted by a lamp in the spectral region that plants respond to. They account for the nutritional value of light and are a direct measure of the light energy available for photosynthesis.