Tests of different DIY household bulb solutions

[LEDTonic]

I tested a GE "Basic LED" ligtbulb (9.5w 60w-equiv, warm and cool). It's their cheap line of bulbs (not dimmable. No CRI mentioned.). I think GE makes it exclusively for Lowes. I don't see anyone else selling it.

I attached an example PDF showing how I'm planning to memorialize the test results (you have to look hard for it. This forum's theme doesn't make links and things stand out well). This is the only one I have, so I can't summarize anything about it. Eventually I'll put this on my Google Drive with other results. I'll have a summary PDF (rank the test results, and link to each test-result PDF). I need to do some more and see how it goes together. (I need to baseline a CFL too. It surprises me how people still hang unreflected CFLs in the air. Comparing a globeless LED lightbulb to one of those is attention-getting. It's like 4x the light for 33% less electricity. It's enormous. At least when I measured lumens.).

When I measured lumens, I was just looking for the brightest light per watt. It will be interesting if any lightbulbs stand out as better in terms of PAR. Getting back to CRI, if you watched one of those DIY spectrometer videos, the guy illustrated how "white" on a computer screen is really just red, green & blue. He points his tube-meter white screen and it's just 3 spikes. It's not a nice blend of the entire spectrum from blue to red.

I wonder if CRI has something to do with that. Maybe that kind of "white" has low CRI because it's such a lousy match to the full spectrum of the sun? And, the higher the CRI, the more complete. If true, then maybe that would be reflected in PAR? (I should try to measure the PPFD of my laptop screen. ha. And the lumens. If there's a big difference, that might mean something.).

Yes, I watched a little of it. Absolutely interesting stuff.
I understand the LCD coloring. My guess is that many different single wavelength diodes could work in symbiosis, creating a very high CRI or even a CRI of 100.
Three single wavelength diodes, can not (but still produce a white light).

The downside is that producing some colors results in a low umol/j. Green, for example, has a low value when created with monochromatic diodes. Red and blue are very efficient and white diodes are just blue diodes with a phosphor coating that will convert some of the blue light into other wavelengths, through fluorescence.

Comparing a white light from a computer screen with white light from a LED-bulb will most likely be very difficult.
If you want to compare umol/j for 3 white diodes vs one red, one green, and one blue diode of the same caliber, I could probably help you figure that out (if I can find the old tests).

Lumens favours green/yellow light and only tells us how bright a light is to us humans.
umol/m2/s or PPFD, measures all wavelengths/photons equally.

As different wavelengths are produced with different efficiency, the PPFD will change based on what colors the light consists of.
It can be:
10% blue, 50% green and 40% red
40% blue, 50% green and 10% red
Both could potentially show roughly the same lumen/LUX, while the light with 40% red can produce a greater PPFD since red light is more energy efficient than blue.
Just an example but you get my point.

So yes, the PPFD will most likely be reflected in the CRI.

Btw I did find some notes. I don't recall if it was Epistar or Bridgelux LEDs, but I've tested a couple of different wavelengths in a sphere to see how they compare.
385nm 0,04 PPF/W -> PPE -> umol/j
400nm 0,6
430nm 1,3
460nm 2,1
505nm 0,8
585nm 0,5
630nm 1,9
665nm 2,6
730nm 0,5

3200k 1,5
4500k 1,5
6500k 1,6
15000k 1,8

Mix and match any way you like.
By the way, it is not included losses for inefficient drivers, lens caps, etc. So the real numbers are lower than this.
Lens caps can produce a greater PPFD/W, but will produce a lower PPF/W.

 

[az2000]

I'm getting some useful results. Using a Kill-A-Watt meter helps to see the light reaching operating temperature. The watts drop as the light intensity drops (as the lightbulb heats up). It's easy to watch that and wait for it to stabilize, or know the range of "actual watts" for the PAR measurements taken.

PAR-38 Flood
I always liked the old glass-lens Cree PAR-38 flood[1]. Based upon the package specs, the L/w seemed high compared to what's available today. It grew well too. (I made the spider fixture <<link for those.). From the new products' packaging, I wasn't expecting anything to be as good. I bought a new Cree PAR-38[2] and it's better!

- The old floodlight averaged 7.3 ppfd/watt:

It actually uses 18.8w. So, that's anther reason to measure actual watts. (It wasn't as good as the packaging led me to believe.).

- The new floodlight averaged 9.21 ppfd/watt:

That's considerably better than the old floodlight. (Maybe the old one was better when it was new. It may have lost some lumens due to use. But, I wouldn't expect that to be more than 10%. The new one would still be better.).

The new floodlight is more concentrated (40- vs 47-degrees). I felt like the 47-deg was a little too concentrated. So, this one might not be as usable that way.

- However, removing the plastic lens: 12.65 ppfd/watt:​

That's more concentrated. But, that's a lot of light for 19w.​

​

That could make a good top light with 18-24" distance. I'm thinking 4 of those floods (lensless) from the top (80w total), each angled a little from the side, for top-lighting around the plant, more coverage, down the side of the plant. And then 4 lightbulbs as sidelight -- close around the sides of the plant from the corners (another 40w). In a 2x2 space, that would be 30w/sq ft. And a lot of intense, penetrating light.​

60w-equiv lightbulbs
I measured my old 10w GE Bight Stiks[3]:

I don't have any Brightstiks still with the globes. I couldn't do my usual comparison with/without globe.

I bought new GE "basic"[1] lightbulbs at Lowes:

That's considerably more light (per watt) than the GE Brightstik. It's possible the GE Brightstiks lost some lumens from being used. But, I wouldn't think it would be *that* much.

Plus, those new "Basic" bulbs are cheap. $1.25 each. (I think I paid $3.50 each for the Brightsticks.). These "basics" are so cheap: use them for one grow, and throw 'em away.

[I also measured the new Cree (60w-equiv with 90+ CRI). It's 2% more light per watt. Not worth the $6 price tag.]

I'm going to measure my old Philips bulbs. I thought they were more efficient than the Brightstiks (my lumen measurements 3-4 years ago.). But, the Brightstiks grew very well. So, I'm sure these GE "Basic" bulbs would be as good, or better.

I'm going to get some new "Ecosmart" (cheap Home Depot) bulbs. It seems like the cheap bulbs are good compared to what I thought was good 3-4 years ago.

[1] Old Cree PAR-38 18w, 90w-equiv, 1500 lumen, 47-degree, flood, 3000k. Glass lens. Photo attached: blue packaging.
[2] New Creee 19w, 150w-equiv, 1200 lumen, 40-degree flood, 3000k. Plastic lens. Photo attached: white box.
[3] Old GE Brightstik 10w, 60w-equiv, 760 lumen, 2850k & 5000k. (I don't think these are made anymore. No retail stores seem to be selling them.).
[4] New GE "Basic" LED, 8.5w, 60w-equiv, 720/760 lumen, 2700k/5000k. (I think these are packaged exclusively for Lowes. I don't see any other stores selling this model. Other stores may sell the same bulb, but a different GE model name. This one is "basic." Not dimmable.).

 

[LEDTonic]

That's more concentrated. But, that's a lot of light for 19w.

1200lm / 19w = 63 lm/w
Sure, it delivers a great PPFD/w in a small area.
But the luminous efficacy.... Or am I missing something?

[I also measured the new Cree (60w-equiv with 90+ CRI). It's 2% more light per watt. Not worth the $6 price tag.]

I also think it is interesting to look at the $/w or lm/$ or PPFD/$.
I found the 9w basics being hard to beat since I bought them in pairs for $2,5/pair. The 14w cost me $7/pcs.

 

[az2000]

1200lm / 19w = 63 lm/w
Sure, it delivers a great PPFD/w in a small area.
But the luminous efficacy.... Or am I missing something?

What do lumens mean to a plant (that ppfd doesnt)? My goal is just to evaluate off-the-shelf bulbs, how they'll potentially grow a plant (without getting into their spectrum. I'd like to have a spectrum graph to add to these readings. But, I don't know if those DIY spectrometers consistent enough for that. I should buy that one in a tube.). I'm not trying to measure the bulb's performance as much as it's performance on a specific footprint that reasonably depicts the amount of plant surface a person would use it on. If I'm doing that wrong, please explain.

Also, I don't think I'd trust the lumens on the packaging. If I were going to weigh lumens, I'd measure lux. (Something that can be verified. Cree's old 18w PAR38 obviously misstated the lumens. It was only a 90w-equiv, but had 2500 lumens. Now the new 150w-equiv has 33% less lumens. I'm not trusting labels too much). I wouldn't care about light going in all directions. Just what's reaching the plant. What I do to help more light reach the plant (removing the globe, reflecting) alters the published lumens (if they were correct, which most people can't ascertain. An, it seems pointless because all anyone really cares about is the amount of lumens or par falling on the plant. At that point a lux or par meter would be the thing to use.

I've been thinking more about that 40-degree floodlight. I'm thinking about drilling 1/2" holes around the perimeter of the lens. I think that might be the best of both worlds (lens or without lens). It would let some light out without the loss of the lense. But, keep the center less concentrated (I think). I think it would let more light out around the sides, creating a better balance of intensity.

 

[LEDTonic]

I'm not trying to measure the bulb's performance as much as it's performance on a specific footprint that reasonably depicts the amount of plant surface a person would use it on. If I'm doing that wrong, please explain.

Don't get me wrong. I just thought 63 lm/w was a strange value to see from a light manufactured by CREE.
That is way down and on the same level as CFLs.
IKEA's "VÄXER" e27 10w LED with red boost is doing 800 lumens at 10w (stated values, haven't confirmed) with 30 degree lenses on.

 

[az2000]

Don't get me wrong. I just thought 63 lm/w was a strange value to see from a light manufactured by CREE.
That is way down and on the same level as CFLs.
IKEA's "VÄXER" e27 10w LED with red boost is doing 800 lumens at 10w (stated values, haven't confirmed) with 30 degree lenses on.

I agree. I didn't think the Cree 40-degree flood sounded good based upon the box specs. But, it measures better than the old glass flood I liked so much.

I measured three Philips all-glass floodlights from Walmart (7, 12 & 14w). They have 8.95, 9.43 & 10.53 ppfd/watt.

And, some GE "basic" from Lowes (11w). It's 8.59 ppfd/watt. I cutoff its lens. There are LED lenses underneath, covering the LEDs. They have 3 phillips head screws holding the LED lenses down. I removed those lenses and measured again. It's essentially a globeless lightbulb. Same ppfd/w for the space I measure. The "reflector" which remains on it adds a bit more performance than a globeless lightbulb without a reflector. So, for $3.25 more, a person could essentially have the $1.25 lightbulb, but without the expense of a reflector (but, almost the same performance as the lightbulb with reflector.).

Anyway, those floodlights (with their lens) are about the same as Cree's 9.21 ppfd/watt. Less expensive than Cree.

I drilled 5/8" holes around the perimeter of the Cree lens. 11 holes. It's pretty open. That increased the ppfd 4%, to 9.54/watt. The center reading remained the same. But, the readings 4" off center are a little higher. Maybe if the holes were larger it would be better. (That seems like an improvement worth doing. It makes it more like the 47-degree flood. Less concentrated in the center (but, not by taking anything away from the center. Just adding a little more light around the edge.).

I'm still debating using these floodlights (without the lens) as high-intensity top-down light. I think spreading those 19w around more (more coverage, gentler/softer/even coverage) would be more efficient (more usable by the plant). But, it's interesting to think of that concentrated light painting the sides of the plant, all the way around, with strong penetration.

If I do that, I'd use the GE "basic" (from Lowes, 11w). Without the lens: it's almost the same ppfd as the 19w Cree (without its lens). 12.02 versus Cree's 12.65. The actual ppfd in the center is 1000 instead of 2000. That lower intensity would be at cannabis's high-end (for what it likes to see at the canopy, from what I've read lately.).

So, figure five of those 11w lenseless from the top. That's 55w. Then another four 9w (60w-equiv) globeless lightbulbs in each corner as sidelight. 36w. Total 91w. That's almost 23w/sq ft. I bet that would grow very well. Add 2-4 more sidelghts late in flower and I bet it would be excellent 28-32w/sq ft.

 

[az2000]

I'm starting to wonder if measuring from a fixed 12" height is meaningless. In real use, some of these lights would be 6" (or less) from the canopy. At 12", a fair amount of light falling outside my 16" square grid.

I measured a GE "Basic" PAR-20 floodlight (6.5w, sold at Lowes, $4.50). Removed the front lens essentially makes it a globeless lightbulb with a reflector built in. At 12" height, I got 5.50 ppfd/watt. That's as good as a globeless lightbulb in a 5-1/2" reflector, without having to buy a reflector. (The only downside is that you pay $4.50 instead of $1.25 for the lightbulb, Reusing a reflector would save some money in the longterm. Basically buying light at 15 cents per watt that way.).

Anyway, I moved that light down until the corners of my 18" grid were 0-1 ppfd. (That turned out to be 6" above the grid.). That creates 11.08ppfd/watt.

That's more representative of how that bulb would be used.

==
I'm starting to think that your circles would be better. I.e. measure 8 & 16" circles. Position the height of the bulb to have 0-1ppfd at a 20" circle. That 20" ring wouldn't be measured, just a reference for getting a proportional height for a bulb. A way to "focus" the light. The height of the light would be variable.

A lightbulb with its globe (diffuse, omni light) might be 2" from the measuring surface (in order to have 0-1ppfd at the 20" circle). A floodlight (with lens still attached, a 40-degree beam) might be 28" high (to get to the point that the light is just starting to fall on the 20" circle).

So, the height would be different for each light. But, that would also suggest how the light should be used. With most light falling in the measured area, its ppfd/w could be extrapolated to different heights.

Is that how you do it? Are you using varying heights? Or, the same height for all bulbs?

I thought the same height for each bulb would make it easy to compare bulbs (apples/apples measurements). But, in real life, the lensed floodlight would be further way, and these low-watt PAR20s would be closer. Measuring the bulbs from non-optimal heights makes it less reliable to extrapolate what it would be at different heights. I was thinking that would be less subjective (using a consistent height for all bulbs). But, a more subjective starting point (optimal height for a bulb) would mean more about its actual use. It would capture more light that could then be scaled up/down if the person wanted to imagine the light being closer/further.

I think that 20-inch ring (where no discernible light should exist) would be a way to make it less subjective.

 

[LEDTonic]

I'm starting to wonder if measuring from a fixed 12" height is meaningless. In real use, some of these lights would be 6" (or less) from the canopy. At 12", a fair amount of light falling outside my 16" square grid.

I measured a GE "Basic" PAR-20 floodlight (6.5w, sold at Lowes, $4.50). Removed the front lens essentially makes it a globeless lightbulb with a reflector built in. At 12" height, I got 5.50 ppfd/watt. That's as good as a globeless lightbulb in a 5-1/2" reflector, without having to buy a reflector. (The only downside is that you pay $4.50 instead of $1.25 for the lightbulb, Reusing a reflector would save some money in the longterm. Basically buying light at 15 cents per watt that way.).

Anyway, I moved that light down until the corners of my 18" grid were 0-1 ppfd. (That turned out to be 6" above the grid.). That creates 11.08ppfd/watt.

That's more representative of how that bulb would be used.

==
I'm starting to think that your circles would be better. I.e. measure 8 & 16" circles. Position the height of the bulb to have 0-1ppfd at a 20" circle. That 20" ring wouldn't be measured, just a reference for getting a proportional height for a bulb. A way to "focus" the light. The height of the light would be variable.

A lightbulb with its globe (diffuse, omni light) might be 2" from the measuring surface (in order to have 0-1ppfd at the 20" circle). A floodlight (with lens still attached, a 40-degree beam) might be 28" high (to get to the point that the light is just starting to fall on the 20" circle).

So, the height would be different for each light. But, that would also suggest how the light should be used. With most light falling in the measured area, its ppfd/w could be extrapolated to different heights.

Is that how you do it? Are you using varying heights? Or, the same height for all bulbs?

I thought the same height for each bulb would make it easy to compare bulbs (apples/apples measurements). But, in real life, the lensed floodlight would be further way, and these low-watt PAR20s would be closer. Measuring the bulbs from non-optimal heights makes it less reliable to extrapolate what it would be at different heights. I was thinking that would be less subjective (using a consistent height for all bulbs). But, a more subjective starting point (optimal height for a bulb) would mean more about its actual use. It would capture more light that could then be scaled up/down if the person wanted to imagine the light being closer/further.

I think that 20-inch ring (where no discernible light should exist) would be a way to make it less subjective.

I agree it can be tricky to find the most useful height.
I'm not sure that each bulb should have its own height. Instead, I think more along the lines that some bulbs should be measured at 2-4", such as 9w CFL and possibly even slightly stronger or weaker CFLs. Maybe a 3-6w LED could also be measured at that height if we think that a bulb of that wattage could be useful in some situation.

In the next league, which is the league where I think most bulbs should be measured, the height of 6" is optimal. This height includes the 9w LED and possibly even up to or slightly above 14w LED (or around 1500 lumens).

Bulbs with focusing lenses play in their own league IMO. I still have the 10w from IKEA and a generic 2.2w with focusing lenses that will be measured. I've just had so much to do lately and so little time. Anyway, both of these have lenses and I am fairly sure that 6" will be too close for both of them, or it could possibly work for the 2.2w. So not only does lamps with lenses play in their own league, but they could/should also be measured at separate heights to get useful data out of them. Very few growers would have useful data of a bulb measured at a height that produces 1500-2000 PPFD in the centre spot, as no one would use it at that height. I think 50-500 PPFD is the most useful intensity overall.

I am measuring these bulbs for growing and I believe that the most useful information to get out of my measurements is what height each bulb should be hung at to achieve a certain relevant intensity. Less interesting is how a 2.2w is performing when hung at the same height as a 10w.

I will be measuring the IKEA-bulb at several heights.
If you are growing basil, hang your lamp at this distance.
If you are growing peppers, hang your lamp at this distance.
If you have a cannabis seedling, hang your lamp at this distance.
If your plant is this big, use two lamps or a bigger lamp.

A grow-bulb sold worldwide that has very little information provided by the manufacturer. Although they are specialized in furniture, so who can blame them.

Again, I know we are measuring bulbs for slightly different reasons, although there are a lot of common points that we are both interested in. I'm just sharing my thoughts and intentions and you can get inspired by whatever parts of this that you feel fits your situation and bulbs. Having one height for all bulbs would be cool but I find it far from practical.

 

[az2000]

some bulbs should be measured at 2-4", such as 9w CFL and possibly even slightly stronger or weaker CFLs. Maybe a 3-6w LED could also be measured at that height if we think that a bulb of that wattage could be useful in some situation.

the height of 6" is optimal. This height includes the 9w LED and possibly even up to or slightly above 14w LED (or around 1500 lumens).

Bulbs with focusing lenses play in their own league IMO.

Probably the mistake I made was using 12" height. If I used 8" or 6" I probably wouldn't have run into a perceived issue of "optimal height." I had already thought about optimal height versus standardized measuring height. But, I believed it could be extrapolated from the numbers. Now I think it would work better to extrapolate "up" from a more concentrated measurement. Not down from a weaker measurement that loses light around the sides (my 12" height in most cases).

So not only does lamps with lenses play in their own league, but they could/should also be measured at separate heights to get useful data out of them. ... 50-500 PPFD is the most useful intensity overall. ... I believe that the most useful information to get out of my measurements is what height each bulb should be hung at to achieve a certain relevant intensity. Less interesting is how a 2.2w is performing when hung at the same height as a 10w.

We're saying the same thing. If the height is static (for a category of bulb), then the 50-500ppfd is variable. What I'm thinking is make the center spot static, and the height variable. Do people care if a bulb is 5.5" or 7"? I'm thinking if the intensity/conservation (upon the measured area) is more normalized (300-400 range), that would be more useful than the height.

Basically, you're already doing that. You just have coarse stops. You have both variable height and variable footprint. I'm thinking of making the height more variable in order to make the footprint more consistent. I think that would be more meaningful (comparable) because that's what people are interested in. Not the height (too much).

It's interesting to think about. My motivation is to conserve light, measure it all, and then have better extrapolation about how much to raise/lower a light to get inverse-squared results. (The way I do it now with 12" height, I don't think extrapolating closer height would be as accurate as if I measured at 8" and extrapolated with that measurement which captured more light which fell outside the 16" grid when measured at 12" height.).

So, I'm thinking of it as a two-fold thing. Should the height be normalized? (do people really care about that?) or should the illumination (intensity/footprint) be normalized. You're doing a "best of both worlds." I'm thinking of making it fine-grained (height, and more consistent(?) light on the measured area.

Coming at it from that perspective, the category-distance would reveal itself after measuring a few bulbs. 8w bulbs with reflectors are in the 8-9" distance. 11w without reflectors are in the 6-7" distance.

It's interesting to think about.

===

Yesterday, after I started thinking about variable height (to adjust the outer edge to my measuring area), I was leaning toward measuring a circle.

But, today I'm liking squares again. Reasons: 1) Measuring all four sides makes it auto-centering. (I try to position the grid under the light so they're balanced measurements. But, at a certain point it seems easier to take 4 measurements than to try to get it perfectly centered and take only one measurement on one side.). 2) The corners sample a different distance. (I.e., there are circles implied in the grid. You could draw squares that intersect your circles. In which case the distance of the squares would be variable from bulb to bulb. The strength at each square would be consistent.).

I think the next thing I'll try will be 6", 12" & 18" grids. But, the 18" grid will only be measured in four places. I won't measure the corners (representing a 25" circle). They'll be used to adjust the bulb height so almost no/little light falls in that space.

It's interesting because we're dealing with the same issues differently. You're using variable height for categories of bulbs. Your "grid" distance is variable, set to round ppfd increments. Mine is fixed distance. You're circles (which can imply squares). I'm squares (each of which implies two circles).

 

[az2000]

PS: I secured a short piece of wood (popsickle stick) to the end of my ruler so I can measure the lightbulb difference without having to involve my par meter probe. I made the extension 1-1/4" inch. That seems to be about the height of the probe.

This is the grid I'm using right now:

The outside corners are only used to set the bulb height (if there's negligible light).

Here is an example of how I'm imagining this working:

The first test: I had the bulb high enough to get the outer corners reading 1 to 2 ppfd (the meter would go back and forth between the two).

The second test: I had the bulb low enough to get 0-1 ppfd (again, the meter fluctuating back and forth).

I think that might be a good way to objectively measure an "optimal" height for a specific bulb. Maybe find those two heights. Then measure the height between the two (in this case 8-3/16"). Or, measure both heights and average the two measurements. (That would be a lot of work. Maybe not worth it.).

This idea will probably fall apart with another bulb (lower watt.). I start thinking "maybe I need different sized grids for different watt bulbs." But, then that would essentially be what you're doing (with different heights for different watt bulbs).

It's like pulling the same 3-4 levers and always getting back to the same place.

 

[LEDTonic]

PS: I secured a short piece of wood (popsickle stick) to the end of my ruler so I can measure the lightbulb difference without having to involve my par meter probe. I made the extension 1-1/4" inch. That seems to be about the height of the probe.

This is the grid I'm using right now:

View attachment 885035​

The outside corners are only used to set the bulb height (if there's negligible light).

Here is an example of how I'm imagining this working:

View attachment 885036​

The first test: I had the bulb high enough to get the outer corners reading 1 to 2 ppfd (the meter would go back and forth between the two).

The second test: I had the bulb low enough to get 0-1 ppfd (again, the meter fluctuating back and forth).

I think that might be a good way to objectively measure an "optimal" height for a specific bulb. Maybe find those two heights. Then measure the height between the two (in this case 8-3/16"). Or, measure both heights and average the two measurements. (That would be a lot of work. Maybe not worth it.).

This idea will probably fall apart with another bulb (lower watt.). I start thinking "maybe I need different sized grids for different watt bulbs." But, then that would essentially be what you're doing (with different heights for different watt bulbs).

It's like pulling the same 3-4 levers and always getting back to the same place.

I admire your approach to this.
Yes, it seems to be a bit of catch-22 when comparing different sized and performing bulbs.

Indeed, a certain level of intensity is more useful for a grower than a certain height. I have been thinking of what bulbs are the most common ones for growing (9w and 14w maybe?), and take more measurements of these. Possibly starting at 7" height, then 6", 5", etc.

Just found one additional bulb at the supermarket. Got it for $5. It has 36-degree lenses so now I have three different lensed bulbs. Generic 2.2w, Philips 5.7w, and IKEA 10w. Hopefully, I will be back with results in the near future.

Do you think it would be useful to measure 9w and 14w at more heights (than 6")? Again, maps with round circles.

 

[az2000]

I admire your approach to this.
Yes, it seems to be a bit of catch-22 when comparing different sized and performing bulbs.

It's not as simple as I thought it was. There are competing goals. The measurements should approximate how someone would use the bulb. Your categorical heights accomplish that (one height for 10w bulbs, another height for 15w). There's also light conservation (measuring as much as possible). If 10w bulb has a globe (but not in a reflector), it would be used much closer to the plant -- and still light would be lost outside the measurement area (a 15" box for me, more about that below. I'm experimenting with different grids.). But, 10w globeless would be a little further from the plant. My 15" grid is about optimal for capturing all the light when the globeless bulb is 5" above the measuring surface. (6-1/4" to the actual grid surface. 5" to the measuring probe.). But, when I put a reflector on, it's too intense in the center. The 15"-grid corners are 0 pppfd.

When I measured lumens a few years ago, I measured from the luminaire's (fixture's) "nearest surface". With the diffusion globe attached, I measured from 6" to the globe. When I removed the globe, I measured 6" to the LED surface. When I put globed or globeless in a reflector, I measured 6" to the rim of the reflector. To me, I was measuring to the "light. The LEDs were moving 2-3" (even though what constitutes the fixture remained 6" from the measuring surface.

I'm thinking that might be the right way to do it. But, admittedly, it breaks the more accurate measurements from the same height. (You can extrapolate the same-height measurements. Changing the height (because "the nearest surface" changes as the bulb's configuration is modified) seems hard to equate from one set of measurements to the other. But.. they seem more representative of actual use.

It's perplexing. My idea for the corners being an "event horizon" didn't work out a well as I thought it would. I was hoping it would be an objective way to find a measuring height. But, I don't think it makes sense. In some ways it's good for finding the height where most of the light lands on the measuring surface. But, it made the height too variable between bulbs. There is something good about having standard heights. (That's where your categorical height works better. 60w-equiv bulbs are better suited for one height. 100w-equiv for another height. Let the differences in bulbs appear within their category. That makes better sense, I think.).

Right now I'm playing with different grids for those categories:

Low-watt grid: 4-8-12"
Mid-watt: 5-10-15"
High watt: 6-12-18" grids

I think that's similar to what you do measuring the circle of the light. You find the even 20,30,40 ppfd "rings." Your ring diameters vary.

I'm still not sold on rings. I might get there. (I usually have to learn the hard way). I like the grid because it has varying sampling distances (the corners of the boxes). There are implied rings. I like measuring all 4 sides because it compensates for any errors centering the grid under the light.

Getting back to the competing goals of measuring. One thing I don't like about the squares is that the corners drag the average ppfd down. That's especially true when I put a reflector on. The light cuts off abrupty. The outer corner can be 0. (But, that's part of why I'm thinking measuring the vertical distance to the lip of the reflector would be better. That causes the grid to be covered better. I think it's more representative of how it would be used.).

Just found one additional bulb at the supermarket. Got it for $5. It has 36-degree lenses so now I have three different lensed bulbs. Generic 2.2w, Philips 5.7w, and IKEA 10w. Hopefully, I will be back with results in the near future.

I like the floodlights (especially with the lens removed). It's basically a globeless lightbulb, but it comes with a reflector. That makes it more expensive (compared to buying just a bulb and using a reflector, which can be reused as $1.25 USD bulbs are replaced. Replacing the floolights can be $4 to $12. Basically replacing the reflector too.).

I think I mentioned before: I think bulb makers are going back to frosted glass, an suspending the LEDs in the center of the globe like "filaments." If that becomes the new normal, the floodlights will be the only useful retail light. I think the loss of reflecting suspended LEDs woul be too much. The big win for the common "lightbulbs" are how the LEDs are surface mounted and face the same direction. Hopefully that doesn't go away.).

Do you think it would be useful to measure 9w and 14w at more heights (than 6")? Again, maps with round circles.

I don't know. I'm taking more measurements and meditating on the results, trying to think of what makes sense.

I wanted to keep it simple. I just wanted to sanity check the bulbs, maybe find a best PPFD/w. Maybe best value/ppfd. I hoped it would be simple, just two grids. Not a lot of measurements.

Now I'm starting to think it may require 2-4 measurement sessions (17 measurements each) and arrive at an overall average. But, I don't want to do that much work. I'm still looking for a reasonable (yet representative) method.

I think you're on the right track with "this height for this category of bulb." I think the measurements should approximate how the light would be used. Varying heights are good that way. But, globed, globeless, reflected... I'm thinking that might imply different heights should be used too. (But, this gets back to my "event horizon" corners to objectively set the height. That's not as good as I hoped it to be.).

 

[az2000]

Here's my latest experiment with distance and grid size (especially trying to understand how to measure globed, globeless, reflected).

This first measurement is simple because it's globeless & without reflector. The nearest part of the luminare is the LEDs. (This is out of order. The "with globe" measurements next have the headings explaining the column meanings.).

Globeless:

To me: globeless is the starting point (reference point) for determining the standard height/footprint for the 60w-equiv class of bulbs. 5" seems a reasonable distance for this globeless bulb (from the plant). At this distance, it fills the 15" grid (with a reasonable intensity).

Maybe 4" would be be better for actual use. (Maybe the grid could be 4.66, 9.33 & 14". But, those are oddball numbers).

The 15" corners are like four samples around a 21" circle. At that distance the light falls off quickly. (If I did 4" height & 14" grid, the corners would represent a 19-3/4" circle.).

With globe:

Here I have a choice to measure 5" to the LED surface (like globeless). But, that's 3" to the globe. (Or, 5" to the globe, which is 7" to the LEDs).

I think 3" to globe is more realistic to how it would be actually used growing. (I don't think anyone would use a globed bulb because it's so lossy. But, it's so much softer & diffuse. If I did use it, I'd put it 3" to the canopy, not 5". Maybe even 1").

I'm not measuring globed with reflector. If someone wants directional light, the answer is to remove the globe. After that, adding a reflector is a small improvement.

[It may not be useful to measure globed. It doesn't have any use other than the "wow factor" for removing the globe. That doesn't need to be demonstrated for each bulb.]

Globeless & reflected:

Again, like the globed bulb, I have a choice between 5" to the LEDs (which would be 3" to the lip of the reflector). Or, 5" to the lip of the reflector (which is 7" to the LEDs).

I realized perhaps what should constitute the light source is halfway into the reflector. This seems seems like a reasonable way to think about what the light "is" with the reflector. It's a reasonable distance to the canopy. A reasonable intensity. (Maybe the globed-bulb measurement should be to that halway point too. Midway into the globe. Just for consistency in comparisons.).

Summary:

I was thinking of taking globed and reflector measurements both ways (3 & 5"), and average the two. But, that's a lot of measurements. Maybe the "halfway" measurement would accomplish the same thing (easier).

Maybe your approach finding even-increments ("rings") of PPFD is better. That's a more dynamic footprint. (I like the ease of moving the sensor to my already-marked locations. It's a mindless activity.). Maybe your way is better, show the intensity of the footprint variably from bulb to bulb (instead of varying numerics in a fixed grid). It looks easier with fewer measurements. (But, you have to work at each measurement, finding the precise spot. And, if it's not perfectly centered, it might not be accurate. Measuring all four sides of a grid compensates for that.).

I'm still not sure what the best way is.

It seems like the goal is to use a height and space (footprint) that's reasonable for use with the plant.

If the height is adjusted to fit the area (like my "event horizon" idea, where the corners should barely have light) then there's a lot of inverse-square loss/gain. Hard to compare one bulb to another (even though the footprint is static).

If the footprint is adjusted to fit the light, (like your circles, which find the natural footprint of the light, not forcing the light into a standard footprint), it seems hard to relate one bulb's footprint to another. But, if the footprint's static (like my grid), it risks not measuring some light falling outside the footprint. Or, having dark areas which drag the average down.

There must be a sweet spot where the light concentration/distribution is optimal. Too high for more coverage, you get inverse square loss. Too low, it covers less -- but the inverse-square loss is reduced exponentially.

I wish there were some way to find that sweet spot for a bulb. A formula where you measure the center, and the distance to the point where the intensity is 1/10th. You plug those two values into a formula, and it tells you the optimal height (to make the most use of the light. Higher, if too intense in the center. Lower to make better use of lower light levels if there's too much of that around the distant edges.). Something that would balance those two extremes.

I think varying the height of the light would be good if there were a precise way to chose an optimal height (a height that would be optimal for growing. Not just for filling the grid, like my "event horizon" idea. And, not variable grids to work with a static height, like your varying footprint.). I feel like there's some holy grail between those two things. But, I don't know how to do it.

 

[az2000]

Do you think it would be useful to measure 9w and 14w at more heights (than 6")? Again, maps with round circles.

You said something before about having different heights for different categories of lights. I think that makes sense. I was originally thinking about doing mine at one height for all bulbs so they could be compared. (That's what I did with lumens.). But, if a 15w would never be used at the same distance as a 5w, (or vice versa) you can't use the numbers to decide *how many* bulbs are needed. (I never thought about that measuring lumens. Now that I measure PAR, I can see how the measurements can directly translate into "need 8.32 bulbs to grow a plant."

So, it seems useful to measure the bulb the way it would be used (example: 5w at 2.5"; 10w at 5"; 15w at 7.5".).

It seems like those categories would be good.

I still wish there was a programmatic way to enter the height, center intensity, and distance to 20% of center intensity, and receive a result saying what the optimal height would be (to maximize the amount of light falling in an area). There must be some way to calculate that. (I.e., if the light's too low, would the more intense light in the center be less usable than if the light were higher -- and that concentrated light spread over more leaves? Or, if the light is high, would it be better to lower it and send stronger light to fewer leaves? Capitalize on the inverse square on a smaller area? Or, capitalize on leaves underutilizing light -- compared to leaves receiving intense light in the center?).

We know how much ppfd a cannabis plant needs in veg or flower. But, I wonder if there's a way to look at that on a smaller scale. If there's 500ppfd falling on a spot, and only 100ppfd falling 10" to the side of that spot... would raising the light make the light more useable over more leaves? Or, would it just be inverse-square loss? Does the first 100ppfd of light trigger more photosynthesis than the last 100? (Reportedly, cannabis's upper range is 900ppfd in flower. You can give more, but it's not used as much. The more above 900, the less used it is. Does that diminishing return work backwards? Is there a point where it's better to blast one leaf with 500ppfd than to split it across 2 leaves as 250ppfd?

Does that make sense? If you have uneven lighting, is 900ppfd (no matter how small that spot is) better than having 500ppfd on a larger spot? It seems like that should be known information (considering how much information is known about how plants grow.). It seems like there would be a way to programatically optimize a footprint into intensity/efficiency versus coverage/loss.

If that were possible, then I could see per-bulb heights being useful. (That's what I was hoping my "event horizon" would do. But, all I was doing was fitting a light to a fixed footprint. That's not optimal height for any bulb. It just confused the numbers).

I think these category heights work for the floodlights if the lenses are removed. At that point they're just globeless lightbulbs with a reflector integrated into it. A 9w floodlight should be almost equal in intensity and coverage as a 9w globeless lightbulb in a reflector.

If a floodlight is used with the lenses, then it should probably have its own category (height). But, I don't know if anyone would grow with such a floodlight. These lights usually have two lenses (outer and one covering the LEDs). Those absorb light. There's a lose refracting the light. The light has to be used at a greater distance because it's so focused and intense. That's inverse-square loss. A floodlight (with the lenses) looks impressive. It looks like it would drive a plant with intense light. But, my logical mind tells me it should result in significantly less light reaching the plant compared to removing the lenses and using it closer.

 

[az2000]

Here's a summary of what I have for A19 60w-equiv lightbulb brands (Lowes & Home Depot):

The bulbs were measured 5" to the globeless LEDs. Or, 5" to the midpoint between rim of reflector and LEDs. (Typically an inch higher to the LEDs.). I'm measuring to the sensor, not the grid surface.

The Cree performs best. But, it costs the most. (Personally, I'd spend $20 extra on lighting. But, the budget grower might prefer the less expensive bulbs. They're not that much different in PPFD/watt.).

These are the old bulbs I used in 2015 (can't buy them now, except maybe overstock/clearnace places online.):

I know those grow. They're in the same range as the new bulbs.

I didn't test any 5000k (daylight) bulbs. They're always 10% brighter, or less watts for the same brightness. (I don't want to get too deeply into it. It's not fun going back and re-measuring everthing because "aha! now I've found the holy grail!").

I'm going to measure 100w-equiv next. (I always like to use 60w-equiv. Spread the watts around better with more bulbs. I was never into the 100w-equiv very much. I used the 19w old Cree glass floodlights instead. I don't know why. Others had used it.).

So far I like the 5" height, 5-10-15" grids.

For 100w-equiv, I'm thinking 6" height and 6-12-18" grid.

 

[LEDTonic]

I think bulb makers are going back to frosted glass, an suspending the LEDs in the center of the globe like "filaments." If that becomes the new normal, the floodlights will be the only useful retail light.

Then we would have to start experimenting with intra-canopy lighting, haha.

I realized perhaps what should constitute the light source is halfway into the reflector. This seems seems like a reasonable way to think about what the light "is" with the reflector. It's a reasonable distance to the canopy. A reasonable intensity. (Maybe the globed-bulb measurement should be to that halway point too. Midway into the globe. Just for consistency in comparisons.).

When I compared globe/globeless and also globeless with homemade reflector, I measured the same distance from the diodes, each time.
For me, it was interesting to compare how the different setups affect the intensity when only one factor is changed, although your ways may be more useful. What exact reflector are your talking about and how does it look? Is it a loose part that doesn't originally come with the bulb? I'd love to see a picture of it.

I wish there were some way to find that sweet spot for a bulb. A formula where you measure the center, and the distance to the point where the intensity is 1/10th. You plug those two values into a formula, and it tells you the optimal height (to make the most use of the light. Higher, if too intense in the center. Lower to make better use of lower light levels if there's too much of that around the distant edges.). Something that would balance those two extremes.

I found this on Samsungs website not long ago. I believe it describes the lm301b model. While it may not be exactly what you wanted, you could potentially calculate height and distance from this type of thinking.

Does that make sense? If you have uneven lighting, is 900ppfd (no matter how small that spot is) better than having 500ppfd on a larger spot? It seems like that should be known information (considering how much information is known about how plants grow.). It seems like there would be a way to programatically optimize a footprint into intensity/efficiency versus coverage/loss.

I've read tons and tons of studies and tests done on all different types of crops/plants in various intensities, photoperiods and spectrums. Unfortunately I don't have any fun sources saved, but generally, the optimal levels were usually around 400-600 PPFD for medium to high light crops (not counting C4 plants). Other than that, many species have lower thresholds on leaves that are on lower levels of the plant, acclimatised for natural shading from leaves growing above. If a leaf gets too much light it will start to dissipate the excess light as heat. Aside from that, there's also the law of limiting factor. While a plant could theoretically utilize around 900 PPFD, all requirements should be met for that to be possible. I'm not saying 900 PPFD isn't a good idea, I'm just saying it may not be for everyone and every situation.

I think these category heights work for the floodlights if the lenses are removed. At that point they're just globeless lightbulbs with a reflector integrated into it

Do you mind sharing one or a few pictures of this? (globeless with reflector integrated)

A floodlight (with the lenses) looks impressive. It looks like it would drive a plant with intense light. But, my logical mind tells me it should result in significantly less light reaching the plant compared to removing the lenses and using it closer.

I agree. Although I'm thinking that this type of bulb is not meant to grow cannabis and is instead more meant for green plants and flowers. Or rather, It is meant to fit people who won't use it in a confined grow space.
I got a monstera as a gift recently but after a couple of weeks it started to lean against the window because of insufficient light (Irrelevant), The IKEA bulb delivers roughly the same intensity and footprint at 20" height as a 9w globeless does at 6". The point is that I rather have this one hanging at 20", than a 9w at 6". The spread of light is completely different as this one can hang well above your head without irritating your eyes, which is almost impossible with a regular 9w globeless bulb.
But most of the times for situations involving cannabis, this is not a problem.

 

[az2000]

Then we would have to start experimenting with intra-canopy lighting, haha.

I had an idea 4-5 years ago to insert low-watt SMD5630 "corncob" lightbulbs into the canopy. I'm probably taking the inverse-square to an extreme. But, I really think that could be powerful; feeding light directly to the leaves. Instead of harsher, single-point light concentrated in one top-down fixture; or 4-6 less-harsh globeless lightbulbs surrounding a plant from 4" distance... lay a dozen 3w omni bulbs on the leaves (light the plant from within, at a 1/2" distance).

20w doesn't sound like a lot. But, at 1" distance, that woul be like 100w at 6" distance. (I'm not saying this would be ideal as the only light source. But, maybe 18w top-down lighting, 10w side lighting, and then a few 3w leaf lighting.). All of them together could be very powerful & manageable.

You can get strip lighting that's IP67(?) encased in plastic. I was thinking about making "light sticks" that you insert through the canopy (light it from within). A dozen "skewers" through the leaves. (Like a scene from Clockwork Orange.).

It sounds crazy. But, I really think this is where the future of lighting is. The efficiency gains are increasingly diminished returns. Delivering light is going to be where grow lights distinguish themselves. If L/w goes from 170 to 200, that pales to the light gain from moving the LED closer to the plant.

When I compared globe/globeless and also globeless with homemade reflector, I measured the same distance from the diodes, each time. For me, it was interesting to compare how the different setups affect the intensity when only one factor is changed, although your ways may be more useful.

It's a tough balance. When I measured lumens a few years ago, I measured 10w and 15w bulbs at the same heights. It was easier to see how the weaker/stronger lights compared directly. But, it wasn't representative of actual use. (In actual use I would have a little more distance for the stronger light).

Back then, even though I use the same height and footprint to measure 10 & 15w, I measured to the nearest edge of the luminaire. (The edge of the globe; the LED surface of a globeless socket; the lip of the reflector when the reflector was used.). I'm doing that to a lessor extent now. (To the center of the globe; the LED surface of a globeless socket; halfway between the lip of the reflector and LED surface).

My concern about keeping the bulb height the same (regardless of globed, globeless, reflector) is that it's not too representative of actual use. Especially with the reflector. It can be very focused. I think changing the height (to represent the changed shape of the light source, its "source of emmission" changing (from the globe, or a reflected surface). I think it evens out the variations.

What I'm doing is halfway between what I did in the past measuring lux (globe, globeless, reflected). But, you're right. It's not as easy to make direct comparisons. It's more subjective.

What exact reflector are your talking about and how does it look? Is it a loose part that doesn't originally come with the bulb? I'd love to see a picture of it.

I use these 5-1/4" & 8-1/2" reflectors which come with Bayco clamp-on light sockets. Home Depot sells these rebranded "HD." (I think Lowes has them as Blue Eagle, or something like that.).

They're very delicate. Paper-thin metal. They have to be stored with some caution (in a bucket with a lid). It's not the sort of thing you'd set on a shelf and let it get bumped around against other things. It will become dented very easily. (In fact, sometimes you have to wait for more stock to arrive at the store because all the units on the shelf are beat up from customers handling them.).

This is another thing that, as LED efficiency becomes a diminishing return, and grow lights have to compete with more ingenuity, it seems like a "lego-like" socket system (reflectors speciically engineered for maximum performance) would be a hot item. Instead of cobbling together socket mounting from hardware (and reflectors that might not have a lot of efficiency engineered into them when they're just intended to light a room while you paint it), there could be a *system* for integrating lightbulbs into a grow space. Interchangeable parts (gooseneck extenders, flex arms, GU-11 sockts for surface-mount applications, GU-11 to E27 adaptors). I think people would go *wild* for stuff like that. Not pure DIY. More like a set of parts that interopeate together with the goal of using ordinary bulbs. (Instead of selling lighting, the focus would shift to selling a Lego-like "fixture" system.).

There are software programs to design reflectors. Povray, Photopia. I haven't looked into it. (I found this page (<<link) on candlepower forums. Search that page for "reflector.").

I've read tons and tons of studies and tests done on all different types of crops/plants in various intensities, photoperiods and spectrums. Unfortunately I don't have any fun sources saved, but generally, the optimal levels were usually around 400-600 PPFD for medium to high light crops (not counting C4 plants).

That's about what cannabis is said to need in veg. In flower it seems like 600-900 is the optimal range. Above 900 is wasted unless CO2 is used.

I don't know much about it. I've never look into it before. But, based upon the lightbulbs I'm measuring, I think I've been doing 300 veg, and 400 flower. Certainly not driving the plants hard. That one grow I did at 18-22w/sq ft (linked to in my first post to this thread) shows that cannabis doesn't need a lot.

Do you mind sharing one or a few pictures of this? (globeless with reflector integrated)

I have attached 3.

The Cree still has the inner lens. I think it clips into the side/base of the reflector. I drilled holes in the outer lens to see if I could make it more usable. I want to play with that more before I try to remove the inner lens and potentially wreck the reflector surface.).

The two GE photos show the inner lens. Those were easy. Just small screws.

I agree that the floodlights could be good for situations like you show with the Ikea light. Aesthetics play a role in some growing situations. I think the floodlights (with lenses) won't be good solutions for growing cannabis because there must be a significant loss having the light 2' away (compared to less intense light close. Making it less intense involves removing two lenses. Those must be absorbing light. Another loss in addition to the inverse-square loss of distance. But, when a plant is getting free light at a window like yours, then it's a tradeoff.).

My mind tells me that's true (about floodlights not being an efficient concentration/use of watts. But... seeing a plant lit up with a floodlight looks impressive. It must just be psychological ("dramatic lighting."). It sure looks like strong light that way could be effective.

I may be thinking of this topic to narrowly. A lenseless light sends light more angles, more coverage. There's more loss that way (light traveling further to the edges of the now-wider footprint). Maybe more concentrated and intense could be more efficient reaching deeper into the plant. (That's why I'm thinking a mix of light types could be good. Stronger, more directional at the top (pointing down). An then broader/closer light around the sides. (And then, maybe a bulb inside the plant lighting it from within.).

 

[az2000]

FYI: I finished testing the 10w- & 15w-class lightbulbs. See attached. The GE "Basic" at Lowes is the best value by far for ppfd/watt (that was your idea to compare them that way).

I included measurements from my old bulbs I've grown with. But, I don't remember the cost. They can still be bought online. But, I don't think they're better than what's out there at the stores today.

I never used the 15w-class (100w-equiv) bulbs much in the past because it always seemed to me the 10w-class (60w-equiv) was more efficient. I got that impression from the boxes' lumens/watts specs, an my lux measurements. I still have that impression, although this time I move the 15w-class bulbs 1" higher, and measure 18" grid (whereas the 10w-class bulbs are 15" grid.). So, it's hard to make direct comparisons this way.

I think the only reason I would use 15w-class is for top-lighting and minimizing the number of bulbs I have to manage. But, I think I'd go to 19w-class floodlights for that instead. (I'm going to start comparing 2-4 of those now. I need to figure out a sensible distance/footprint for that class of bulb. (Hopefully I don't have another idea about this, and have to go back and re-measure the lightbulbs again. That's getting old.).

 

[LEDTonic]

You can get strip lighting that's IP67(?) encased in plastic. I was thinking about making "light sticks" that you insert through the canopy (light it from within). A dozen "skewers" through the leaves. (Like a scene from Clockwork Orange.).

If you are actually looking for a fitting flexible led strip that is good for growing, you might want to take a peek over at r/SpaceBuckets, if you haven't.
There are some truly nice builds in there as well:

I use these 5-1/4" & 8-1/2" reflectors which come with Bayco clamp-on light sockets.

That one looks like it could reflect light a lot better than the homemade reflector I tried in my video, which only created a hot spot.

That's about what cannabis is said to need in veg. In flower it seems like 600-900 is the optimal range. Above 900 is wasted unless CO2 is used.

I see now that my last message was a bit confusing: " the optimal levels were usually around 400-600 PPFD for medium to high light crops (not counting C4 plants) ".
To clarify; increasing light intensity with 10%, from 200 PPFD to 220 PPFD, would give 10% greater yield/result/growth/rate of photosynthesis. This rule may also apply from 400->440. But is there still a 10% gain of photosynthesis when you increase from 600-660? Or 800->880?
Somewhere down the road, light intensity starts to pass on its role as the limiting factor for photosynthesis. The "optimal" level I was referring to, Is just before this starts.

The two GE photos show the inner lens. Those were easy. Just small screws.

I haven't seen bulbs like that in the stores where I buy my bulbs. I have a quite different (and very basic) selection to choose from. Thanks for all the pictures.

I may be thinking of this topic to narrowly. A lenseless light sends light more angles, more coverage. There's more loss that way (light traveling further to the edges of the now-wider footprint). Maybe more concentrated and intense could be more efficient reaching deeper into the plant. (That's why I'm thinking a mix of light types could be good. Stronger, more directional at the top (pointing down). An then broader/closer light around the sides. (And then, maybe a bulb inside the plant lighting it from within.).

A mix of lights would be interesting to play with. Overall, I am sure that an intensity that is as even as possible is the best option. Lenseless lamps are not a bad thing, as long as all photons ends up where we want them, on our plant. When I think about it, the photons emitted in a SpaceBucket should be utilized pretty well and with a pretty even intensity from bottom to top. If we could re-create this scenario somewhat but with e27bulbs, I think it could be a homerun. It would be a fun project, to say the least (and probably a happy plant).

FYI: I finished testing the 10w- & 15w-class lightbulbs. See attached.

That is some great data. Good job!

 

[az2000]

I haven't seen bulbs like that in the stores where I buy my bulbs. I have a quite different (and very basic) selection to choose from. Thanks for all the pictures.

You attached a photo of a floodlight you bought. I bet if you cut the front lens off (if it doesn't pry off. Some do with care and effort), I bet it would be like the ones I showed. There's probably a primary lens covering the LEDs. If you remove the front lense, it will be more concentrated. If you remove the lens covering the LED too, then it becomes essentially a lightbulb with surface-mounted diodes (and a reflector) integrated to it.

I've seen the space buckets. I like that idea of surrounding a plant with light that way. With lightbulbs, it wouldn't take many sockets to put that much light on a plant.

You saw the spider fixture (<<link) I made. It has folding arms:

I've been thinking about how those arms would work mounted from the tent legs (folding horizontally, not vertically). The socket could be retracted back into the corner (against the tent leg), or extended 12" into the plant space for smaller plants.

I use 3/4" PVC "coupler" fittings to make light mounts that attach to my tent poles.

The lamp is at the pole. To extend it, I have to use those flexible goosneck extenders to extend the socket.

The folding arm is made of 3/4" square wood. It fits snuggly into a 3/4" PVC "T" fitting's side outlet. The "T" fitting could be the tent leg mount. And the folding arm could be bolted into the "T" outlet side. (Like I said, the folding action would happen horizontally, not vertically.).

I'll have to make one.

I like this idea because it gives the lights more reach, more flexibility to adapt to the size of the plant. But, without having to buy those gooseneck extenders. It would be all DIY which anyone could. Because they'd operate sideways (not up and down like the fixture), you could have 4 on a leg.