Light Intensity; LED vs HID

[ttystikk]

You can only drop your light until the point of highest intensity damages your plants.

If you have one high power source over your canopy (HID or a highpower cob), you have really high intensity in the middle of your beam that is limiting how low you can drop your light and its giving the edges the shaft. (Somewhat mitigated by a quality reflector)

If you have 16 low(er) power points of light (say 35w a piece) then you are only limited by the highest intensity in the middle of one of those beams. You can drop your light a lot lower when the highest concentration of photons is coming from the center of a 35w emitter rather than a 1000w emitter.

Prefab units are not clustered together in a box because that is a good design for light distribution. Its just easier to build/ship a luminaire that way. The best designs have as many diodes as you can afford, driven as softly as you can afford, spread out as evenly over the canopy as you can logistically manage.

Like this;

 

[ttystikk]

Problem is that a 100W HPS doesn't come close to the efficiency of a 1000W HPS. Especially not to a double ended HPS.

A 100W HPS gets about 1.4umol/s/W from the bulb and a proper 1000W HPS produces 2.1umol/s/W from the bulb.

No problem. Just use COB LED!

 

[OneHitDone]

That is not true either

You get overlap from those 10 FL's and with that you will get roughly the same "penetration". It's not identical since the light is spread out better, but in the middle the HID will win and around the edges the 10 FL's will win. On average you will see the same "penetration".

We are talking about at a distance from the source

 

[Funkraum]

There was an old chart somewhere with regard to distance and light bulb etc. at the time of the chart the 400watt hps bulb won.

i like lights, any light is a god send to an indoor grower

 

[captainmorgan]

There was an old chart somewhere with regard to distance and light bulb etc. at the time of the chart the 400watt hps bulb won.

i like lights, any light is a god send to an indoor grower

The problem with out dated charts is it doesn't take into account the huge increase in output of the latest gen LEDs.

 

[Funkraum]

yep its a fair point you make, but its a good place to start, if you have a Dimmable ballast and your reflector are on pulleys i suppose you have the best of both worlds?

getting the light spread though is really important, and will make for a bumper crop of course dependent on healthy plants

 

[Rahz]

If the 100w and 1000w had the same efficiency, then hanging 10 100w bulbs in a room, or 1 1000w in the room... the center point reading would be higher under the 1000w considering the way light is spread under bulb/hoods. However, the PPFD in the room would be almost the same. The only difference will depend on how much light each setup casts on the walls. If the walls were 100% reflective then the PPFD would be the same. This would also hold true regardless of how high the bulbs were hung.

 

[Funkraum]

you could alter you reflector closer to the wall and and have the centres reflector more open pushing the light source deeper. i understand what you are saying the light bonces? is that what you are saying

 

[captainmorgan]

yep its a fair point you make, but its a good place to start, if you have a Dimmable ballast and your reflector are on pulleys i suppose you have the best of both worlds?

getting the light spread though is really important, and will make for a bumper crop of course dependent on healthy plants

Another problem I've noticed with these older charts is most seem to use very poor quality ( low efficiency ) LED fixtures to take readings off of which compounds the difference.

 

[Airwalker16]

 

[Funkraum]

i am out on quality fittings, there is quality, and then there is realistic prices, leds are expensive, that being said, i do have some led bars

i have a friend with gavita pro series lighting, and i still get better weight than him, and he run a sealed room with c02

 

[ttystikk]

Another problem I've noticed with these older charts is most seem to use very poor quality ( low efficiency ) LED fixtures to take readings off of which compounds the difference.

This is because LED has made such impressive advances in the past 5 years or so.

 

[ttystikk]

i am out on quality fittings, there is quality, and then there is realistic prices, leds are expensive, that being said, i do have some led bars

i have a friend with gavita pro series lighting, and i still get better weight than him, and he run a sealed room with c02

COB LED isn't so expensive anymore.

Your buddy with gavita lighting is having the classic 'more isn't better' problem, lol

 

[PurpleBuz]

It showed that to be true earlier in this very thread. W/ the SK, Illumitex, & HPS. The drop was much less.
@OneHitDone explains it using the fish tank in water. Same concept. (Good ex.)
But I am in no way coming back to this thread to argue or even participate any further. Just answering a question that was quoted to me.

no its false go study the physics of light.

 

[Funkraum]

hay purplebuz its how you cook the books, or give the bleeerb., if the merchant stop trying to sell us chrome wheels all good in the hud

 

[PurpleBuz]

Like this;
View attachment 3739501

love the show and tell. Nice to see cob vertical in action!

 

[OneHitDone]

View attachment 3739524

What happens to those cob #'s at say 36"?

 

[BM9AGS]

What happens to those cob #'s at say 36"?

Malocan ran multiple height tests and the change was in no way following my naive interpretation of the inverse square
Law. That law does not apply when using more than 1 light source or reflectors or lenses.

 

[ttystikk]

Malocan ran multiple height tests and the change was in no way following my naive interpretation of the inverse square
Law. That law does not apply when using more than 1 light source or reflectors or lenses.

Sure it does; it just applies to all of them working together.

 

[OneHitDone]

COB LED - Defying Inverse Square Law since 2016