? For Lighting expert..

I have a question.thanks for stopin in

If 2 models of a a 12 bar light has the excat same setup L x W wise
One has a ppfd of 2000 at 24 in
One has a ppfd of 1000 at 24 in
Could u simply run the one with lower ppfd at half the distance (12 in ) to achieve the same end means.?

There was a website that gave a example .
And im not excactly posiyive on the numbers. But..
One light offers 3.5. Umols/j
The other 2.1 umols/j
The example was that. The one at 3.5 would be 33 percent more efficent..
So could u not move the light at
2.1 umols/j
33 percent closer? To achive the same means

A 1000ppfd is actually very good especially for flower if you’re on a budget, the more efficient light is definitely better

Thank u but that is noth the question the question is
If the less efficient light is. 33 percent less
Cant u move the light 33 percent closer
To have the same result as the mlre efficient light

Get a light meter.

In Micro moles per joule no, the 2.7 3.5 whatever your light says it is is how much "food" (photon micromoles) the plant can receive in a Given timeframe. The 3.5 being more and therefor more efficient in delivering food (light)

To answer your question, yes.
The light that you bring down will lose coverage as well.
The better light can be hung @24 inches and flower a 3x3 space.
The light that you bring down will lose half of that ability and only have a 1x1 coverage.
You also get more heat the closer you get.
On top of that, if you lower it too much then it can possibly shadow under the light @ 24” losing even more coverage.
List goes on

The closer to the canopy the light is the less light is lost on the walls.

Moflow said:

The closer to the canopy the light is the less light is lost on the walls.

Click to expand...

So in essence. Wouldnt a lower watt closer top the cannopy ne as effective as a higher watt further away.. it seems to me running at 36 in away is a huge waste

Fibromyoucha said:

So in essence. Wouldnt a lower watt closer top the cannopy ne as effective as a higher watt further away.. it seems to me running at 36 in away is a huge waste

Click to expand...

it would cover a smaller area wit higher intensity. just like any other light source

mauricem00 said:

it would cover a smaller area wit higher intensity. just like any other light source

Click to expand...

What if it was a bar light so lets say u have a 1000 watt ,42 x42 in, 12 bar light on a dimmer and its run suggested at 30 in over canopy.. couldnt u lower the power to 500 watts. So by half. And lower the hight by half To 15inch over canopy And have about the same results.. because the bar light is still covering the same space?

as you lower the light the footprint shrinks and the intensity goes up.

Well if you grow in an open scenario, or are this type of grower that grows in a bunker with black walls (lolwtf) this pic


can be used as a 'rule of thumb' of how your light behaves... (strictly the formulaes in the wiki only apply to a situation without any reflection)

But since you are a tent-grower, that is, most of the photons emitted are trapped inside and will be reflected until they are absorbed by a pigment - which, in a filled tent are mostly the leaves, the pots, and some general loss as there simply isn't a 100% reflective material out there... so, depending on the invested wattage you use your lights create a certain amount of photons, and these are there, no matter at where you place the lamp.

So, just to make an example, same lamp but dimmable, you either run the lamp on 1000w, or dim down to 500w, then the 1000w will create twice the amount of light (this may vary dependant on what kind of hardware you use...)

And, as others have mentioned, the distance towards the canopy has a tremendous influence on the footprint, and also center heat spot, your lamp creates... the goal is to arrive at 700-1000ppfd *flux density* for the leaves in flower, and how you reach this under your setup is up to you. Now if you have a stripe setup you could drive it down to a point blank range and dim it also down considerably, but then, there won't be much light for the other leaves under the canopy... in contrast, placing hid lamps in closed hoods at the top of a closed tent may give best uniform spread, but you can't just add mindlessly lamps you want, as at some point, it'll burn your leaves or create too much heat.

Your 2*315 ceramics in a 4x4 is plenty already.