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Offlinepha3r0
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Re: The [Re: DungenessDank]
    #359072 - 02/07/10 10:05 AM (14 years, 1 month ago)

Quote:

DungenessDank said:
What really is important is what is the plant itself using to produce its energy. I think spectrum and coverage matters much more for marijuana than the overall light a bulb produces. How much of that light is going to waste vs how much light is the plant using.

Not to change the debate, but this MJ cultivation :rasta:




Well put. So who knows everything about photosynthesis? I guess really you can pick apart any one aspect of cultivation and find pieces to debate over but you can have a full sized sun in your grow room and if you forget about the rest of the process you get nothing.


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"The proverb warns that, "You should not bite the hand that feeds you." But maybe you should, if it prevents you from feeding yourself."
- Thomas Szasz

"if you arent good with electricity dont go touching it...ive electrocuted myself twice...its no fun"
- mhbound

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InvisibleHarry_Ba11sachM
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Re: The [Re: pha3r0]
    #359078 - 02/07/10 10:23 AM (14 years, 1 month ago)

even amongst the scientific community theres a grand debate over photosynthesis and artificial lighting. In one camp they say that plants utilize the full spectrum from high frequency ultraviolet all the way down to far infra-red and that growing without the full broad-spectrum will yield deficient results. The other camp looks at graphs of peak photosynthetic efficiency and claims that since chlorophyll, xanthophyll and carotenoids all have their specific peak wavelength that putting energy into producing light at any other wavelength is just a waste of energy. I wish I had an answer for you, but professional biologists and botanists haven't even agreed on an answer yet. :shrug:


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OfflineKine
Registered: 11/25/08
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Re: The [Re: pha3r0]
    #359101 - 02/07/10 10:52 AM (14 years, 1 month ago)

Lol. random good time for this to resurface...

Got to talk with a CFL/Energy Star rep the other day.  He agrees with me that lumens cant add.  Its just illogical to say that 2 lights with the same max out put would when put in proximity produce twice as much light (in theory of course).  What your doing is trying to achieve that max output over all areas of your room...

I think what the real problem here is our Vocab.  We keep using the wrong word to describe things.  Lumens is used in reference to one singular object.  As soon as your adding any proximity around that, secondary bulbs, ect... your now referring to lux.  Cause your not talking about one single location.  You've now added space between and have to calculate for that; thus making it lux.

I just feel that it would go like that.  Say you have a 1x1x1ft room.  You put one candle in there.  The flame rests right dead center of the room.  Your producing 1 Lumen. (candle foot watt)  So then you take and you fill from wall to wall with candles, your able to stuff 25 in there.  You'll have a 25 lumen room... but your max output is still only 1 lumen.  However, your lux will be somewhere around say 2 lumens per sq inch.  Because every 2 inches; you have a candle over lapping one other; where one candles max output stops; the other one picks it up and brings it back to max lumens...

I feel this is an argument just like T5 vs MH.

@ Pha3r0 - I know some.  Photosynthesis when taking place in doors goes on PAR ratings.  I forgot what it means; but its a reading of the useable light for plants.  Its hard to find anything on it; but i found someone who has ran extensive testing of bulbs and actualy built a par reading machine and used it in a light measuring machine... the only down side is so many damn numbers and large words with massive deffinitions ment it was hard for me to decipher what the results were saying...

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OfflineKine
Registered: 11/25/08
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Re: The [Re: Harry_Ba11sach]
    #359103 - 02/07/10 10:54 AM (14 years, 1 month ago)

Quote:

Harry_Ba11sach said:
even amongst the scientific community theres a grand debate over photosynthesis and artificial lighting. In one camp they say that plants utilize the full spectrum from high frequency ultraviolet all the way down to far infra-red and that growing without the full broad-spectrum will yield deficient results. The other camp looks at graphs of peak photosynthetic efficiency and claims that since chlorophyll, xanthophyll and carotenoids all have their specific peak wavelength that putting energy into producing light at any other wavelength is just a waste of energy. I wish I had an answer for you, but professional biologists and botanists haven't even agreed on an answer yet. :shrug:




Interesting.  Hadent heard this... i had thought they came down to refining it to "Par" is the useable light... but then again; i dont know what "Par" consists of lol...

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OfflineTrueHerbCrystal
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Re: The [Re: Harry_Ba11sach]
    #359104 - 02/07/10 10:54 AM (14 years, 1 month ago)

Whoa dude! You totally got my mind blown!

Might the Liquid and chronic I'm on, but wow! I think you just settled the debate: there is no answer because the even the science community does not know how much energy plants are using from artificial light.

"chlorophyll, xanthophyll and carotenoids all have their specific peak wavelength that putting energy into producing light at any other wavelength is just a waste of energy."

So what you are saying here is that scientists do NOT know the "optimum" wavelength (or range of different wavelengths) of a plant photosynthetic organelles, being chlorophyll, xanthophyll and carotenoids

Too make it more difficult, is it possible that marijuana has special photosynthetic organelles that other plants do NOT have because they are used by Cannabis spp. in the production of the psychoactive resin in the female flowers. I mean, the fact that a plant can make crystalline solids on its leaf surface, that when vaporized to the point of combustion, there are psychoactive in mammals (reptiles?). I mean, what other plant can perform such an unusual task.

I mean, a "flower" is used by plants for pollination by either insects or wind, and this plant produces a sticky resin in that same area as the psychoactive flower. Whats that resin flower for anyway? Is it to capture the pollen flying in by the wind? Makes sense, but that its psychoactive, whaaaa....

Anyway, that's another debate: Why does female marijuana flowers produce crystalline Resin on their surface? What function does it have for the plant itself?

Harry, You are the smartest guy I Currently know.
~ TrueHerbCrystaL ~

Edited by TrueHerbCrystal (02/07/10 11:24 AM)

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OfflineDungenessDank
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Re: The [Re: TrueHerbCrystal]
    #359107 - 02/07/10 11:00 AM (14 years, 1 month ago)

If god made one plant especially for man to use, it was marijuana.

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InvisibleHarry_Ba11sachM
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Re: The [Re: TrueHerbCrystal] * 1
    #359114 - 02/07/10 11:10 AM (14 years, 1 month ago)

Carotenoids, xanthophyll and chlorophyll are merely the pigments within the chloroplasts (photosynthetic organelles) that absorb the light. scientists have figured out down to the single nanometer exactly which wavelengths are absorbed best by each of these pigments. this is the "PAR" that kine referred to, PAR standing for Photosynthetically active radiation. 
The problem here is that although there are certain peaks where the pigments absorb best, they still do work at other wavelengths. just because they're best at one color doesn't mean that all the other colors are useless :shrug: see this graph for an example.


Lumens are useless in this debate anyway since they in no way have any bearing on the activation of photosynthetic organelles. the only necessary measurement is the intensity of the light source.

Quote:

Too make it more difficult, is it possible that marijuana has special photosynthetic organelles that other plants do NOT have because they are used by Cannabis spp. in the production of the psychoactive resin in the female flowers. I mean, the fact that a plant can make crystalline solids on its leaf surface, that when vaporized to the point of combustion, there are psychoactive in mammals (reptiles?). I mean, what other plant can such an unusual task.




You are absolutely correct, very good inference :thumbup:  From the little research that's been done it's been speculated that UV-B is the specific wavelength for catalyzing production of THC but unfortunately until MJ gets classified in a schedule that allows medical research nothing concrete can be published :nonono:


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OfflineKine
Registered: 11/25/08
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Re: The [Re: TrueHerbCrystal]
    #359122 - 02/07/10 11:32 AM (14 years, 1 month ago)

Quote:

TrueHerbCrystal said:

Anyway, that's another debate: Why does female marijuana flowers produce crystalline Resin on their surface? What function does it have for the plant itself?

Harry, You are the smartest guy I Currently know.
~ TrueHerbCrystaL ~




Its a pest deterrent... as well as an attractant lol.  Dont know why the THC is produced; assuming to disorient the pests it deters...

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InvisibleHarry_Ba11sachM
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Re: The [Re: Kine]
    #359126 - 02/07/10 11:36 AM (14 years, 1 month ago)

both reasons; pest deterrent and sunscreen


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OfflineDungenessDank
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Re: The [Re: Harry_Ba11sach]
    #359131 - 02/07/10 11:47 AM (14 years, 1 month ago)

So is the current accepted theory that the trichome absorbs the UV radiation from the sun? I remember hearing something about this and the creation of THC-V (?) but I didn't know if this was hearsay or a widely accepted thing.

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OfflineTrueHerbCrystal
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Re: The [Re: Harry_Ba11sach]
    #359135 - 02/07/10 11:52 AM (14 years, 1 month ago)

"Pest deterrent" huh...interesting...natural nature is amazing!

That explains why its psychoactive: its likely a poison to non-mammal animals such as worms or chiggers (can alligators get stoned? Komoto Dragons? Anyone?).

"Sunscreen" too....what is it protecting? The sites here the pollen is picked up?

And thanks Harry for finishing my thought...I wanted to say that because of the science community's inability to research marijuana plants, such as the types of photosynthetic organelles it has in comparison to other plants, because of its current laws that classify it as a "controlled substance", preventing research from happening on this very unique (botany wise) plant.
I mean, sticky resin as a pest deterrent, genius....nature's genius, our discovery.

But you said it better Harry, I no make sense no more.

But those topics really don't deal with lumens or lux units or whatever we are calling them now.

For clarity, here's a def. from my dictionary program.

"Lux (noun) - A unit of illumination equal to 1 lumen per square meter; 0.0929 foot candle"

So, Lux is a unit that uses the lumens multiplied to a 2-Dimensional surface area (square meter or square foot).

I think I'm confused
~ TrueHe4bCrystaL ~

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OfflineKine
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Re: The [Re: TrueHerbCrystal]
    #359148 - 02/07/10 12:19 PM (14 years, 1 month ago)

Quote:

TrueHerbCrystal said:
"Pest deterrent" huh...interesting...natural nature is amazing!

That explains why its psychoactive: its likely a poison to non-mammal animals such as worms or chiggers (can alligators get stoned? Komoto Dragons? Anyone?).

"Sunscreen" too....what is it protecting? The sites here the pollen is picked up?

~ TrueHe4bCrystaL ~




So can you give me an example of unnatural nature?  :malamute:

But yes; alligators and komoto's can get stoned (we got my friends bearded dragon stoned often lol)... why couldnt they?  It'd be the same if they ate mushies... but somehow i doubt alligators and komoto's are weeds natural predators that the THC helps protect against...

And as sunscreen its to protect the plant itself entirely.  This is why you get trichs on stems as well.  UV rays are harmful in everyway.  While humans; and plants both need small ammounts of UV; the sun puts out more then enough! (Humans only need like 15 min/day)  So without the trichs; all those UV rays would harm the plant.  So the trichs absorb some of that UV ray.  Then the other trichs act as bug trap (thats why its all sticky icky icky)...

And yes, lux and lumens are retarded confusing.

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OfflineKine
Registered: 11/25/08
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Re: The [Re: DungenessDank]
    #359153 - 02/07/10 12:24 PM (14 years, 1 month ago)

Quote:

DungenessDank said:
So is the current accepted theory that the trichome absorbs the UV radiation from the sun? I remember hearing something about this and the creation of THC-V (?) but I didn't know if this was hearsay or a widely accepted thing.




THC-B i believe.  Then theres also CB1 and CB2's as well... lol.  There was some "Marijuana Man" on you tube awhile ago where i learned about this.  Then found it on ICmag and such.  But yea it was basically people throwing a UV bulb in grows and noticing a increase of trich production (cant say THC entirely; because not every Trich has THC and we dont know if UVB's increase the THC trich; or other trichs...)

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OfflineDungenessDank
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Re: The [Re: Kine]
    #359160 - 02/07/10 12:28 PM (14 years, 1 month ago)


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InvisibleHarry_Ba11sachM
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Re: The [Re: Kine]
    #359164 - 02/07/10 12:33 PM (14 years, 1 month ago)

actually you have that exactly backwards. the quantity of trichs doesn't change, but since UVB is the photosynthetic catalyst for THC synthesis then increasing UVB concentrations directly correlates with an increase in potency

http://www3.interscience.wiley.com/journal/120019839/abstract?CRETRY=1&SRETRY=0

I know you can't read the full article, but in a little bit I'll sign on through my universitys VPN client and upload the entire study for further examination


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Offlinechucklehead
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Re: The [Re: TrueHerbCrystal]
    #359165 - 02/07/10 12:37 PM (14 years, 1 month ago)

OFF TOPIC

Quote:

TrueHerbCrystal said:

Too make it more difficult, is it possible that marijuana has special photosynthetic organelles that other plants do NOT have because they are used by Cannabis spp. in the production of the psychoactive resin in the female flowers. I mean, the fact that a plant can make crystalline solids on its leaf surface, that when vaporized to the point of combustion, there are psychoactive in mammals (reptiles?). I mean, what other plant can such an unusual task.

I mean, a "flower" is used by plants for pollination by either insects or wind, and this plant produces a sticky resin in that same area as the psychoactive flower. Whats that resin flower for anyway? Is it to capture the pollen flying in by the wind? Makes sense, but that its psychoactive, whaaaa....

Anyway, that's another debate: Why does female marijuana flowers produce crystalline Resin on their surface? What function does it have for the plant itself?

Harry, You are the smartest guy I Currently know.
~ TrueHerbCrystaL ~




TrueHerbalCrystal, you are excused from being silly by virtue of your highness.

Organelles are inside cells.  Glads are organs.

I've read that the glands collect pollen, and protect the plant from insects, fungus, and even harsh environmental conditions.  The fact that it has psycoactive properties is what has made the plant so successful.  Similar to that fact that apples are sweet and thus they are successful.  Humans found them, liked them, and so cultivated them, in so doing we selectively bred them for mutations preferable to us.  E.g. Sweeter apples, larger apples,  disease resistant apples, weed that gets you higher and so on.  Or take corn.  Corn ears were never so large as they have been in the last 200 years. 

There are plenty of other plants that get you high.  That wasn't a 'plan' it is just a mutation that so happens to work for us.  Just like there are a bunch of plants that kill us or make us sick. 

I can't do the subject justice.  Check this out.

http://www.pbs.org/thebotanyofdesire/lesson-plan-sweetness.php

ON TOPIC

Regardless of the distance of the lights or their position in space relative to the surface what matters is the light that reaches that fixed surface.  So given that the additional lights can reach that same surface the lux (the light that does reach the surface) will add up in a linear way.  I think the hang up here is people are mixing up lumens and lux and thinking light output = light received by the surface.  The example that comes to my mind is me standing outside on a clear night.  I look up into the sky.  I can see lots of stars at the same time when I look at a fixed point in space.  Which means beams of light from those stars that are light years away from me are hitting my retinas at the same time.  Obviously all of the light being output by those stars isn't reaching me.  Otherwise chucklehead would be vaporized.  So with each additional star more light from far away points in space is getting to the surface of my retinas (a relatively small fixed surface area very far away from the origin of the light). 

Another example I think about is the gamma knife.  Since I lack the skill to describe it well myself I'll provide this link and a quote

http://survivethejourney.blogspot.com/2009/03/gamma-knife-radiosurgery.html

Quote:

Quote:

201 "beams" of cobalt-60 gamma radiation are focused on the region to be treated. The beams go through the skull in different spots, with each beam too weak to hurt normal tissue. However, when they all come together in the area to be treated, they are then strong enough to destroy the tumor. It is a type of single-fraction radiosurgery.










Also who is arguing CFLs are as good as HIDs?  This argument is about adding more lights (no matter the type) and what effect that will have on light received by a fixed surface area near by.

Bottom line for me is this.  Is the addition of more lights better for my plant?  Looks to me like the answer is yes.  More light gets to a given surface area and more surface areas are receiving light.


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OfflineKine
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Re: The [Re: chucklehead]
    #359282 - 02/07/10 02:08 PM (14 years, 1 month ago)

Quote:

chucklehead said:

ON TOPIC

Regardless of the distance of the lights or their position in space relative to the surface what matters is the light that reaches that fixed surface.  So given that the additional lights can reach that same surface the lux (the light that does reach the surface) will add up in a linear way.  I think the hang up here is people are mixing up lumens and lux and thinking light output = light received by the surface.  The example that comes to my mind is me standing outside on a clear night.  I look up into the sky.  I can see lots of stars at the same time when I look at a fixed point in space.  Which means beams of light from those stars that are light years away from me are hitting my retinas at the same time.  Obviously all of the light being output by those stars isn't reaching me.  Otherwise chucklehead would be vaporized.  So with each additional star more light from far away points in space is getting to the surface of my retinas (a relatively small fixed surface area very far away from the origin of the light). 

Another example I think about is the gamma knife.  Since I lack the skill to describe it well myself I'll provide this link and a quote

http://survivethejourney.blogspot.com/2009/03/gamma-knife-radiosurgery.html

Quote:

Quote:

201 "beams" of cobalt-60 gamma radiation are focused on the region to be treated. The beams go through the skull in different spots, with each beam too weak to hurt normal tissue. However, when they all come together in the area to be treated, they are then strong enough to destroy the tumor. It is a type of single-fraction radiosurgery.










Also who is arguing CFLs are as good as HIDs?  This argument is about adding more lights (no matter the type) and what effect that will have on light received by a fixed surface area near by.

Bottom line for me is this.  Is the addition of more lights better for my plant?  Looks to me like the answer is yes.  More light gets to a given surface area and more surface areas are receiving light.




I am pretty sure gamma ray and photons act different... but i cant be positive.  So i dont know just how well that applies... but i see where your going with it...

And no one is arguing CFL is better then HID.  If anything; i said T5.  And what i was getting at is that its a never ending argument.  You say toe-mato; i say tomato.  Also; the bottom line is not "if adding more lights is better" the bottom line is "do adding lights INCREASE the max light output."  Thats what this is moreso about...

Cause one group says adding lights will increase over all light output.  And the other says it does not. 

The way i look at it is that if you have 10 2700 lumen CFL's in a 2x2 room, you can have a Lux of 6750/sq ft, but your max lumen output is still only 2700 lumens.

Others say that in the same situation you'd have the same lux; but your lumens would then be 27000 lumens.

I just dont get that.  Lumens is a measure of light as taken in by the human eye.  A 400w HID puts out 30,000 lumens. it would take 4 7900lumen 150w CFL's to equal the lumen output.  But i can stare at 4 150w CFL's.  It hurts; but i can see the spiral bulb, nothings distorted.  But when i looked at my 400w Lumatek; i couldnt even look directly at the bulb for more then a nanosecond before my eyes wanted to bleed. And lumens is a measure of the light that the eye takes in right?  So obv if my eyes are taking more light; its going to hurt more.  The more it hurts; the more lumens its making.  So why does it hurt the same to stare at one CFL as it does 5 CFL's?  Because your Lumens arent going up, but your lux is..

So how lumens can add doesnt make sense to me.  Cause; yes; lumens can add in the fourm of lux.  But like in my last example it hurts my eyes more to look at the HID then the CFL's... and lumens are a direct output of light as measured by the human eye (1 candle foot watt that the human eye perceives).  So that would tell me that 1 HID is putting out more light then 1 CFL (obv), but even when i stack CFL's, the HID is still more intense.  Just now the CFL's can keep that max output over a larger footprint then if it was just one bulb...

But as previously stated; and now revisited - lumens probably dont even matter to plants.  I see people that sware by light penetration and have lights x inches away ect ect make phat colas.  But then i can look at other people who have the light far away supposedly out of the "effective" range as posted by many charts on sites get just as large; or larger colas.  So how can that be possible to get a nice cola at the bottom of the plant when others cant and keep saying "Oh well light only penetrates so far"... nah... you just cant grow very good.  And more light is not always better.  You can bleach and burn from to much light...

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InvisibleHarry_Ba11sachM
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Re: The [Re: Kine]
    #359326 - 02/07/10 03:30 PM (14 years, 1 month ago)

I'm a little disappointed that you're lecturing us on light behavior and you're not even familiar with the basic tennets of light spectrum chromatography :nonono:
Gamma is merely another wavelength of light. ALL light is made of electromagnetic waves, which is the way in which photons travel through our interpretation of time/space. The heat you emit from your body is photons of large wavelength, UV is photons of a high wavelength, gamma is photons of the highest possible wavelength (that we can detect with current technology. I will basically guarantee in the future we'll discover something else).


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OfflineTrueHerbCrystal
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Re: The [Re: Harry_Ba11sach]
    #359548 - 02/07/10 08:10 PM (14 years, 1 month ago)

Just for everyone's reference on light wavelenghts, here's a diagram of the electromagnetic spectrum...



^ Note that the middle picture row has an unusual scale. Its for "Frequency", and the photos they put there are how "tall" the peaks of the wave are from eachother. Take the microwave lined up vertically with the photo for "Humans", is that a radiowave has a size of about a height of a human, head to foot (~5.5ft).

Also note how narrow the visible light spectrum is in comparison to the rest of the spectrum, its only a small fraction of the radio-to-gamma wavelenght range.

Hope that helps people with some of the confusion on the light spectrum. Hey Harry, can you calculate color temp, such as 2700 K using nanometers of a given light wave? It seems like they are directly related....

Let Me know if theres a way
~ TrueHerbCrystaL ~

Edited by TrueHerbCrystal (02/07/10 08:20 PM)

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Offlinechucklehead
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Re: The [Re: Kine]
    #359559 - 02/07/10 08:17 PM (14 years, 1 month ago)

I think I like the term Irradiance for explaining electromagnetic radiation on a surface.  This is the word I've been looking for to describe my scenario.  I don't quite have all of the math to fully mathmatically explain multiple artificial light sources but I think is taking me in the right direction.  Particularly when you look at the example of solar irradiation below.  Where E adds in a linear fashion.  Also this link helped a little.  But right now I don't have the time to fully investigate this article.  I.e. sit down with the math for a while.

http://en.wikipedia.org/wiki/Gaussian_beam

What I'm having a little trouble with is whether or not the E from two identical CFLs is fairly equal.  If I had to guess the answer is yes.  Which I think means I= [(constant)/2][total E]^2.  So the more lights the more E.  If you have more E then you have more I.  But like I said I have to sit down with the math from the above article to really sort out the E.  Probably need some more information beyond that too.  Maybe I can check the manufacturers websites and find E from a few CFL.


http://en.wikipedia.org/wiki/Irradiance

Quote:


Irradiance
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Irradiance, radiant emittance, and radiant exitance are radiometry terms for the power per unit area of electromagnetic radiation at a surface. "Irradiance" is used when the electromagnetic radiation is incident on the surface. "Radiant exitance" or "radiant emittance" is used when the radiation is emerging from the surface. The SI units for all of these quantities are watts per square meter (W/m2), while the cgs units are ergs per square centimeter per second (erg·cm−2·s−1, often used in astronomy). These quantities are sometimes called intensity, but this usage leads to confusion with radiant intensity, which has different units.

All of these quantities characterize the total amount of radiation present, at all frequencies. It is also common to consider each frequency in the spectrum separately. When this is done for radiation incident on a surface, it is called spectral irradiance, and has SI units W/m3, or commonly W·m−2·nm−1.

If a point source radiates light uniformly in all directions and there is no absorption, then the irradiance drops off in proportion to the distance from the object squared, since the total power is constant and it is spread over an area that increases with the square of the distance from the source.



[edit] Technical details
The irradiance of a light wave is given in terms of its electric field by

,
where E is the complex amplitude of the wave's electric field, n is the refractive index of the medium, c is the speed of light in vacuum, and ε0 is the vacuum permittivity.

Irradiance is also the time average of the component of the Poynting vector perpendicular to the surface.

[edit] Solar energy
Irradiance due to solar radiation is also called insolation. The global irradiance on a horizontal surface on Earth consists of the direct irradiance Edir and diffuse irradiance Edif. On a tilted plane, there is another irradiance component: Eref, which is the component that is reflected from the ground. The average ground reflection is about 20% of the global irradiance. Hence, the irradiance Etilt on a tilted plane consists of three components: Etilt = Edir + Edif + Eref.[1]

The integral of solar irradiance over a time period is solar irradiation. Irradiation is measured in J/m2 and is represented by the symbol H.[1]










I found this under a wiki search on the word light.  I found it informative about why one thing looks brighter than another.
http://en.wikipedia.org/wiki/Light
Quote:

Light is measured with two main alternative sets of units: radiometry consists of measurements of light power at all wavelengths, while photometry measures light with wavelength weighted with respect to a standardized model of human brightness perception. Photometry is useful, for example, to quantify illumination intended for human use. The SI units for both systems are summarized in the following tables.

[edit]

The photometry units are different from most systems of physical units in that they take into account how the human eye responds to light. The cone cells in the human eye are of three types which respond differently across the visible spectrum, and the cumulative response peaks at a wavelength of around 555 nm. Therefore, two sources of light which produce the same intensity (W/m2) of visible light do not necessarily appear equally bright. The photometry units are designed to take this into account, and therefore are a better representation of how "bright" a light appears to be than raw intensity. They relate to raw power by a quantity called luminous efficacy, and are used for purposes like determining how to best achieve sufficient illumination for various tasks in indoor and outdoor settings. The illumination measured by a photocell sensor does not necessarily correspond to what is perceived by the human eye, and without filters which may be costly, photocells and CCDs tend to respond to some infrared, ultraviolet or both.









As far as Gamma vs Visable light Wiki to the rescue. 

http://en.wikipedia.org/wiki/Electromagnetic_spectrum


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