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hardy  Aroids)" <ARISAEMA-L at NIC.SURFNET.NL> Aroids)" <ARISAEMA-L at NIC.SURFNET.NL>
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From: Al Wootten <awootten at NRAO.EDU>
Subject: Re: Grow Lights
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G=F6te 

Indeed, the inverse square law controls light levels (interesting aside=
--I
believe that this law was first expressed by Dante in The Divine Comedy=
),
one of the most important laws an astronomer uses as it allows one to=2=0=

measure the distance to objects whose brightness one assumes one knows
(though more often does not).  I used a fixed distance 
to a white patch which filled the viewfinder.  Since the plants tend to=

get larger with age, moving the lights closer works only within limits.=

But my camera died and my new one is too automatic, as you note, so I n=
o 
longer track light levels.

The first tips of daffodils are breaking ground here...a very warm wint=
er
so far.

Al    
+----------------------------------------------------------+
|Al Wootten, Slacktide, Sturgeon Creek at the Rappahannock |
|Astronomer (http://www.cv.nrao.edu/~awootten/)            |
|NoWorkAllPlay homepage  http://members.tripod.com/~astral |
|Deltaville, Virginia 23043                                |
+----------------------------------------------------------+
G. Svanholm writes:
> At 14:37 2006-01-17 -0500, you wrote:
> >At  1/17/2006 11:03 AM, you wrote:
> >>  you should probably replace them after about 6-8 months
> >>-Ken Mosher
> >
> >A cheap light meter will let you use them until they burn out. Just=
change 
> >the distance to the plants as they age.
> >
> >Ray 
> 
> If you have not got a dedicated light meter you can use your camera =
and see
> what exposure it suggests (unless it is an automatic-automatic-autom=
atic.)
> 
> I miss information here. Light levels decrease with the square of th=
e
> distance so distance is very important. What distances are yo uusing=
=3F
> 
> G=F6te