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Mars-Hydro Epistar 160 PAR Specification Is Misleading

Thread starter #1
Hi, I have a question for anyone that represents Mars-Hydro LED Grow Lights.

I bought an Epistar 160 recently, and my decision to purchase that particular model was based on the advertised PAR 'footprint' specification, 2'x4' for bloom, and 3.5'x5' for veg. I started getting into the specs for the grow light, and realized the marketing material provided by Mars-Hydro was not accurate. I was wondering if you could speak to the inaccuracy of the attached specification. It is not to scale. In a way that is deceptive.

I've redrawn the spec sheet in a CAD program that attempts to provide a to-scale version of the Mars-Hydro specification. I've attached it as well. This will show you the discrepancies that I believe I have discovered.

Thanks in advance.
 

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TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017

SmokeSara

Well-Known Member
Hi HappyFarmers, thanks for the kind feedback, since it is made by our engineer, I will forward your suggestion to them, and let them check their draw again. :D
 

PurpleGunRack

Well-Known Member
Basically none of their PPFD readings are correct because the squares are not to scale to the foot values, this goes for most of their lights and it's been like this for more than a year, dispite many people like you making them aware of the problem.


You don't need an engineer to see that the squares' actual sizes compared to each other don't correspond with the values on the squares, this is 4th grade geometry...

1,5 * 1 = 1,5 sq. ft.
3 * 2 = 6 sq. ft.
3,5 * 2,5 = 8,75 sq. ft.

Now it's obivious that the outer square should be labelled 3x2, since it's actually 4 times bigger than the inner square...
So the middle square should be labelled 2x1,5 which is 3 sq. ft., aahhhhh twice the size of the middle square and half the size of the outer square..... :)

So the correct foot values are:
1,5 x 1
2 x 1,5
3 x 2


And the PPFD values in the lower left corner of the inner box are not correct, they can't be higher than the middle and they are of course not 400 micromoles higher than the opposite corner...
 
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TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
And the PPFD values in the lower left corner of the inner box are not correct, they can't be higher than the middle and they are of course not 400 micromoles higher than the opposite corner...
Testing performed at the remote facility... on the third floor of the Leaning Tower of Pisa, lol?
 

SmokeSara

Well-Known Member
Here is another PAR test data sheet for 18'', and 15'' and 12'' height; Hope this one helps! The data is tested by the integrating sphere tester which needs to put the whole light inside so data won't lost. The real data when using the light might have some different (inside highly reflective tent cloth, data might increase, or inside some place with light leaks might decrease).
1547533179031.png

1547533816918.png

1547533850333.png
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
The data is tested by the integrating sphere tester which needs to put the whole light inside so data won't lost. The real data when using the light might have some different (inside highly reflective tent cloth, data might increase
I would assume so; there will be no more gross light output, of course - but it's probably a safe guess that a tent correctly sized for the light will confine that light into a smaller volume, so the numbers within that space should be higher.
 
Thread starter #13
Here is another PAR test data sheet for 18'', and 15'' and 12'' height; Hope this one helps! The data is tested by the integrating sphere tester which needs to put the whole light inside so data won't lost. The real data when using the light might have some different (inside highly reflective tent cloth, data might increase, or inside some place with light leaks might decrease).
View attachment 1697719
View attachment 1697727
View attachment 1697728
Given that the Pro II 160 provides a rectangular footprint of radiation, this post confused me more than anything.
 
Given that the Pro II 160 provides a rectangular footprint of radiation, this post confused me more than anything.
When a light source is tested professionally, for design purposes they use one of these.


Test-LED-Lumen-CRI-Power-Factor-Inventfine-Brand-Big-Light-Source-Integrating-Sphere.jpg
 
Here is another PAR test data sheet for 18'', and 15'' and 12'' height; Hope this one helps! The data is tested by the integrating sphere tester which needs to put the whole light inside so data won't lost. The real data when using the light might have some different (inside highly reflective tent cloth, data might increase, or inside some place with light leaks might decrease).
View attachment 1697719
View attachment 1697727
View attachment 1697728
These should be on the website as they are correct, the values on the website are far away from this.

You should always use a quadratic layout like this when measuring PPFD, not rectangular like on the website.

For full understanding a square representing the actual size of the light should be added ;)



Given that the Pro II 160 provides a rectangular footprint of radiation, this post confused me more than anything.
It's the correct way to do it, the values will show the intensity and the numbers *should* draw a rectangular (oval) footprint in your mind ;)

Take ie. the blue square (24x24) at 12'' (the last one) and notice the values on the left and right sides are almost twice that of the upper and lower sides of the same quadratic square, this shows the light's footprint is not quadratic :)
 
I would assume so; there will be no more gross light output, of course - but it's probably a safe guess that a tent correctly sized for the light will confine that light into a smaller volume, so the numbers within that space should be higher.
If the photons that would hit the 4x4 line are contained in a 3x3 tent, these are reflected AKA not wasted like they would be in an open area, so you get more light on plants in a 3x3 tent than you get on plants in a 3x3 space in an open area, from the same lamp.
Same deal as when you get more light from a HID bulb when using a reflector, same output as a naked bulb, but focused towards the plants ;)
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
the Pro II 160 provides a rectangular footprint of radiation
Not 100% accurate. Better to envision it as a vaguely rectangular-shaped thing, comprised of many overlapping circles (from the reflector cups). Thus, the "rectangle" will never have arrow-straight sides. Add to that the fact that a stream of photons doesn't behave exactly like a stream of water.

Same deal as when you get more light from a HID bulb when using a reflector, same output as a naked bulb, but focused towards the plants ;)
I have been thinking about reflectors recently...

When a light source is tested professionally, for design purposes they use one of these.

View attachment 1697917
For some reason, I thought it'd be bigger, maybe 10' (or 3m, I suppose) in diameter. I don't know why, though. And... COOL, lol. I wish I had one in the basement ;) .

I'm wondering... Does using an integrating sphere - while such a device is of course capable of capturing every photon emitted by a lighting device and, thus, able to show exactly how much light energy the products produce... If this rather expensive piece of kit doesn't end up sort of understating the power of those products? I am not feeling especially "word-proficient" right now (obviously, sine that isn't one :rolleyes: ), so this might not translate very well. But:

I thought it somewhat odd - or at least less than optimum, from a seller's point of view - to show graphics of a light's output across a space that is, realistically, significantly larger than the space that the light is capable of usefully illuminating. If a customer is thinking about purchasing 50 of the same product for a large room (warehouse?) grow, then this might be useful to know.

I have an older light product from a different company. I am not positive, but I believe that they produced their charts by setting up a 4'x4' "room" - with reflective walls - and using a handheld meter to spot-check readings at the intersections of the lines in a grid in which the lines were spaced 6" apart. Does this directly measure the gross output (total number of photons produced) of the light? NO. But it does show how much light is "hitting" each of those spots on the grid - which can be assumed to be the top of one's full canopy, lol, in a four-foot square tent/space. Had they used an integrating sphere to do this, the numbers they listed might have been lower (guessing, there). The photons that would have been "lost to the greater environment" with one of those (at least a large one) were, instead, reflected back onto the "playing field" by the walls of the hypothetical grow space.

I've seen videos of tests where the people were testing different wall materials (materials with different reflectivity). They did the same thing, created a grid of sorts and tested each intersection (where the lines in the grid cross) with some kind of PAR meter. Even just switching to a more reflective material produced a noticeable increase in the readings. Had they then removed those walls and retested, those numbers would have tanked (fallen significantly).

I recently got a pair of SP 150s and will be using them in my next grow. After having seen the charts for this product, I became... concerned. Now that I have thought more about the testing procedure, I realize that their output in a confined volume of space of the proper size, will appear higher in practice (and to the plants within that space, which is all that really matters here). Same gross output, of course - but more net, so to speak. I am also thinking that these lights could benefit - or to be more precise, the plants under them could benefit - if there was some kind of reflector along their edges. Nothing fancy, just a piece of (hopefully, highly reflective) straight metal, angled so as to concentrate their output onto the footprint that the average user would have. Since they are advertised as being great in pairs in a 3'x3' space, maybe make the pieces along the long sides adjustable to some degree, IDK. I wouldn't think the short-dimension of the pieces would have to be very large (maybe two or three inches at a guess). Just something that would help decrease the distance that the "stray" photons would have to travel before hitting the plants' chloroplasts. With things as the way they are now, the photons that don't travel directly downward to strike the plants - and, since there do not appear to be lenses/reflectors of any kind on the individual diode groups, there will be a LOT of those - have (remembering the inverse square law of lighting) a pretty lengthy path to travel. Those photons which exit the diodes at a shallow angle (again, many of them) have a lengthy path, indeed, since they may strike the walls quite a few times before "finding" a plant surface. The initial angle makes all the difference (again, with no reflective device added to the product). For a mental image, consider the game of pool. A simple one-rail shot into a corner pocket doesn't require a great deal of energy. Decrease the angle so much that, instead of hitting one rail, the ball must hit/rebound off both rails multiple times... and you have to hit the cue ball quite hard. We want to decrease the number of photons that are (pseudo-) randomly bouncing around in the grow room, and increase the number of photons that are either (optimally) traveling directly from the light to the plant or (next best thing) only "bouncing" off of a non-plant surface once. This will never be perfect in an atmosphere, of course, which is one reason why shining a flashlight in an otherwise dark room allows us to see (dimly) some things that are not directly in the "cone" of light - molecules in the atmosphere can cause some deflection of the photons, so to speak. But we cannot grow plants in a vacuum, lol.

I wish my fabrication skills were better, my hands were younger, and I had some kind of photon-measuring device (aka "light meter," preferably one that is set up for PUR or even just PAR). I can - and probably will, before it's over with - deal with the first two, but I won't have any way to test any additions I make to my lights other than my poor human eyeballs. Which are poor, indeed, for measuring light output other than "brighter" or "dimmer" (and even that only with a fairly significant change). However, I should still be able to make some (really rough) judgments - assuming that the reflector material is actually reflective, less visible light on the tent walls to the sides of the light devices should correlate to more light down below. But it would be nice if I had some way to actually measure this.

Light is a funny thing, in the physics sense. Some of us even speculate that a photon has an infinitesimal - but non-zero - mass. Probably not many scientists, lol... But it would go a ways towards explaining some great mysteries in the science world and... well... Occam's razor and all that. If the mass of each photon is so small as to not only not be measurable, but also not even be directly perceivable, and the size of the universe so large that the average amount of light in any given size of volume effectively zero, that's still potentially a HUGE amount of mass in total. Dark matter, lol? Maybe it's actually light matter. Perhaps not, IDK.
 

SmokeSara

Well-Known Member
Yes, we are working on update the data on our website, as they are not updated for some times now;
We draw the PAR in a square shape, but the data is not the same in the same circle, so you still need to check the coverage depend on the data. :Namaste: