How bright does sunlight have to be to beat HID's?

[Tabbatha]

Yo yo,


I'v been googling and gooling and googling to try and find out whether it's better for new plants (say, 2-3wks old) to be put under an HPS bub or whether clouday-day sunlight is better.

Now, I understand that sunlight is always better than bulb-light, but the question in this:

How bright does the sunlight have to be before it's better than an HPS bulb?

If it's a cloudy day outside, would the light coming onto the windowsil still be better than an HP bulb, or does it need to be sunny sunlight?

Any answers would be appreciated as I'm struggling to find an answer to this on the net.


Cheers.

[BudMan]

Well i know its not exactally answering your question, but i know the sum emitts the equal light to 1300w per sq meter... I would assume thats on a sunny day tho...

Good question

[Tabbatha]

Well i know its not exactally answering your question,

It does in part, thanks for posting.

but i know the sum emitts the equal light to 1300w per sq meter... I would assume thats on a sunny day tho...

Interesting.. didn't know that but it sure helps.

Cheers BudMan.

[BUD MIESTER]

http://www.littlegreenhouse.com/guide3.shtml

could be useful to people..

[M_C]

100 lux Very dark overcast day
320–500 lux Office lighting
400 lux Sunrise or sunset on a clear day.
1,000 lux Overcast day or typical TV studio lighting
10,000–25,000 lux Full daylight (not direct sun)
32,000–130,000 lux Direct sunlight

The difference between the units lumen and lux is that the lux takes into account the area over which the luminous flux is spread. A flux of 1000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1000 lux. The same 1000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux. Mathematically, 1 lx = 1 lm/m2.

I'll let you do your own maths as I don't know what HID light you refer too...

[Tabbatha]

Mystery, that's really useful.

I currently use a Sunmaster 250w dual spec, but I'll do my own 'mathing' from here. Thanks a lot pal.