Top bin COB comparison

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Greengenes707

Greengenes707

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BOBBY_G said:
only if the light source is the same distance!

800 canopy ppf from a far light source (HPS, the sun, etc) will penetrate a lot more than 800 canopy ppf from a close light source (T5, etc)

if youre running your 3070s harder at teh same distance = same same

if youre putting your 3070s closer to make up ppf = big difference
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BOBBY_G said:
dissipation watts, no, the 4*25 would put out more light than 1@100

if yyoure talking par watts well 100 par watts is 100 par watts
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augusto1 said:
Let me see if I undertood, 4 cobs @ 25 watts or 2 cobs @ 50 watts will have the same penetration of a 100 watts cob?

Thanks In Advance.
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No one ever understands penetration(actually @Abiqua does just fine)

I love how everyone thinks that the inverse square law means lights "goes away"
-it doesn't disappear....it spreads out. IF you interact with the spread(reflect it back such as a tent)...it is completely moot.
Also...google inverse square...IT ONLY APPLIES TO A SINGLE POINT SOURCE.
-based on the math I've seen so far from people here...none have even looked up the proper equation for multiple point source...let a long where to even begin with it.

On addition to lack of knowledge...how many have put light sides confirmed reflective tents and measured them???anyone here?
Or compared it to open space???


800µmols has the same penetration as 800µmols...that is how it works.
YOu can manipulate shit all you want(height, spread, distribution, whatever) but 800µmols only has 800µmols worth of photons and this worth of penetration and photosynthesis.


Your guys hps comparison is pretty flawed and easily explained.
250w hps...30% efficient
1000w hps 36-40% efficient
1000w has more light and thus more penetration.
MAke it equal efficiency, wrangle the light...and you have equal penetration.
 
dandyrandy

dandyrandy

Well-Known Member
QUOTE="Fastslappy, post: 12267768, member: 920361"]I just wanna fat greasy buds ,
throwing 32 3590's into a 5 x 6' x 8' tall room with 8 each 185's meanies pushing 1400
we'll see what happens
"More is better "[/QUOTE]
I run 800w of vero 29s in 46" x40" area. Rock hard buds.
 
BOBBY_G

BOBBY_G

Well-Known Member
Greengenes707 said:
No one ever understands penetration(actually @Abiqua does just fine)

I love how everyone thinks that the inverse square law means lights "goes away"
-it doesn't disappear....it spreads out. IF you interact with the spread(reflect it back such as a tent)...it is completely moot.
Also...google inverse square...IT ONLY APPLIES TO A SINGLE POINT SOURCE.
-based on the math I've seen so far from people here...none have even looked up the proper equation for multiple point source...let a long where to even begin with it.

On addition to lack of knowledge...how many have put light sides confirmed reflective tents and measured them???anyone here?
Or compared it to open space???


800µmols has the same penetration as 800µmols...that is how it works.
YOu can manipulate shit all you want(height, spread, distribution, whatever) but 800µmols only has 800µmols worth of photons and this worth of penetration and photosynthesis.


Your guys hps comparison is pretty flawed and easily explained.
250w hps...30% efficient
1000w hps 36-40% efficient
1000w has more light and thus more penetration.
MAke it equal efficiency, wrangle the light...and you have equal penetration.
Click to expand...
some good points but youre assuming everything gets reflected 100%. if what you say is true people wouldnt even use reflectors in tents and hang their lights as high as possible. theres a lot of spaces in your garden. there is only one canopy. you need to get the light intensity right *in that spot*. you dont want a uniform 600 umol all ove rthe place you want 800-1000 on your tops and less than 200 on your bottoms/trunks/media
 
BOBBY_G

BOBBY_G

Well-Known Member
PSUAGRO. said:
You wouldn't consider an hid bulb in a REFLECTOR a single point light source though ;-).......inverse square law has always been mute for most setups.

Penetration is a "fuzzy" term..........ha
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'moot'

and inverse square law still applies for each point source (or mostly point source for a reflector), its just the intensiteis are summed with other sources
 
Fastslappy

Fastslappy

Well-Known Member
I run 800w of vero 29s in 46" x40" area. Rock hard buds.
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I have a comparison grow I did in there as I did 3 each 900 watter & 3 each 400 watter mars 2
OK real watts was = about 1800 watts @ the wall
I had a good spread for what they were & foil bubble wrap as wall reflection
this time Orca on the walls
I fill my room No walkway , those plants R on wheels (HF dolly /tub/bungee)
 
Greengenes707

Greengenes707

Well-Known Member
BOBBY_G said:
'moot'

and inverse square law still applies for each point source (or mostly point source for a reflector), its just the intensiteis are summed with other sources
Click to expand...
I'll let you rewrite the laws of physics and plant physiology then. You are apparently aware of something that the whole scientific community isn't. Let us know when you can change quantum processes.
 
BOBBY_G

BOBBY_G

Well-Known Member
unless its a tightly focused beam like a laser its gonna spread out. light from a reflector can be considered a point source (a bulb isnt even a point source) for doing the very simple calculation of inverse square law

for example, take 2 tents. keep them closed so you have no light leakage. put the same amount of T5s 6" above your canopy in one tent, and on the roof of the other tent. would you expect the same results?
 
stardustsailor

stardustsailor

Well-Known Member
Quickies ...


1 ) There's no such thing as "penetration" ...
Photons / energy packets / quanta either get ABSORBED or REFLECTED or
TRANSMITTED .

So ,clarify me one thing :When-any of you- refer to penetration ,what exactly do you mean ?
The amount of light that reaches the lowest parts of the plant(s) ?
The amount of light that is being transmitted throught the upper canopy to the lower ?
The light reflected ,towards the lower canopy ?
The light absorbed by the lower canopy ?
Or is it one word to describe all these ?


2 ) Inverse Square Law: " Single point source "

Single = One single source.Not multiple ones stacked on top of each other ,
or any otherinstallment ....

Point: That's the key word .It means "dimensionless" .Just a point.
The light source has no physical dimensions ...

Of course ,Inverse Square Law applies ,for all real life light sources,but
with some extra equations, for the light source having actually physical dimensions.
Let alone the extra equations for multiple light sources ....

3 ) A "closed " reflective (growing )space has a completely different behaviour to photons,than an open space . A carefully designed reflective surrounding, can have losses up to 20% of total emitted PPF,due to absorption of photons from other matter,
other than leaf tissue .An open space can have up to 80% losses of PPF ....

So ,in many cases a light of 300-400 umol/sec inside a reflective space,
gives the same or even better results than a light source of 1000+ umol/sec
installed in an open growing space ....


Cheers.
:peace:
 
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stardustsailor

stardustsailor

Well-Known Member
BOBBY_G said:
unless its a tightly focused beam like a laser its gonna spread out. light from a reflector can be considered a point source (a bulb isnt even a point source) for doing the very simple calculation of inverse square law

for example, take 2 tents. keep them closed so you have no light leakage. put the same amount of T5s 6" above your canopy in one tent, and on the roof of the other tent. would you expect the same results?
Click to expand...
Lasers do spread out( aka diffuse ) ,no matter how much parallel the beam is focused ...
There's a pretty good reason ,that professional cutting lasers are made in the Infra Red region and not being blue ones or violets or even green ones ...

The light of lasers is coherent .
And trully monochromatic .All the photons are i.e. 405 nm .Not one at 404 nm or 406 nm ..
Those are the biggest differences than light from any other light source ...

https://en.wikipedia.org/wiki/Coherence_(physics)
http://amasci.com/miscon/coherenc.html
 
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wietefras

wietefras

Well-Known Member
Wow, a few weeks ago people were ready to burn me at the stake for saying that inverse square law doesn't really apply in grow tents/rooms with reflective walls, that you can't use open space PPFD matrices to indicate PPFD levels in a grow tent, that PPF (minus losses) divided by surface area determines average light density (plus most of the concept of penetration), that people generally use the concept of penetration incorrectly and that reducing the beam angle with a reflector does not increase "penetration" unless at the cost of surface area covered.

Just wanna repeat that what stardustsailor so eloquently stated, that it's not just the quantity of light, but also a measure of how diffuse the light is. In that sense one 800umol isn't the same as another 800umol. In fact greenhouse tests with diffuse screens have shown improved plant production even though these screens absorb some light. But then sunlight is about is non-diffuse as you can get.
 
Rahz

Rahz

Well-Known Member
A T5 setup doesn't provide a lot of penetration because it's not a lot of light. Take the best T5s available and pack them in as tight as possible and you still won't get the light density of a 600w HID in a 4x4 (or 600w of cobs). IE- 2 400w CFL panels (in a 4x4) isn't as much light as a 600w HID.

PPFD is an average density measurement and is a good indicator of penetration. There is some sense in the idea that a single point light will provide more penetration, but not across the whole canopy. The PPFD directly under the light will be higher (more penetration) and lower off to the sides (less penetration). This is true to some extent regardless of reflector being used.

Multiple light sources will not change the "overall" penetration, instead increasing it on the sides and decreasing it in the middle. This is a good trade off except in the case where the whole space isn't being used (which is not great).

The more light sources you have, the closer to the plants you can get. There is no penetration penalty for having a light close to a plant. Equal PPF from two different lights will provide similar penetration but the emission pattern needs to be taken into account. It would be wrong to hang a 600w HID 6 inches from a full canopy in a 4x4 and it would be wrong to hang a 400w CFL 3 feet from the plants in a 2x4... for obvious reasons I hope. But as I opened with, CFL -vs- HID is unfair from the start because CFL is a weak ass light.
 
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