The Modified Black Box Thread

Dana Riddle

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The light is 8" from the waterline and 24" to the sand bed. I'm also trying to cover 30" width so I'm thinking I may need use 120s.
I was curious about effect of lenses, so went into the lab to take a look. I used a 3-watt green LED (easy to see) and took a PAR measurement with no lens and measured the diameter of the light's footprint (PAR of 39 and a lighted circle measuring 46mm in diameter.) When I placed a 40-degree lens on the LED, the light footprints PAR fell to 11, and the illumination circle became indistinct but something on the order of 65mm. With a 60-degree lens, PAR fell to 8 and the light pattern larger but 'fuzzy.' Some of the PAR loss is undoubtedly due to absorption by the lens itself (not sure how much though.) It is obvious that blending of colors is increased by higher degree lenses. Maybe you've got all this figured out already but it did make me curious enough to spend a few minutes in the lab.

lens.jpg
 
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Jonathan Troutt

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I was curious about effect of lenses, so went into the lab to take a look. I used a 3-watt green LED (easy to see) and took a PAR measurement with no lens and measured the diameter of the light's footprint (PAR of 39 and a lighted circle measuring 46mm in diameter.) When I placed a 40-degree lens on the LED, the light footprints PAR fell to 11, and the illumination circle became indistinct but something on the order of 65mm. With a 60-degree lens, PAR fell to 8 and the light pattern larger but 'fuzzy.' Some of the PAR loss is undoubtedly due to absorption by the lens itself (not sure how much though.) It is obvious that blending of colors is increased by higher degree lenses. Maybe you've got all this figured out already but it did make me curious enough to spend a few minutes in the lab.

lens.jpg
Wait so a 40 degree thens is supposed to focus the light beam. And youre results show that par fell? I feel like most black boxes have 90 degree lenses on them

And if the trend continues with your data that would mean even less par. So is it better to run without lenses?
 

Dana Riddle

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Wait so a 40 degree thens is supposed to focus the light beam. And youre results show that par fell? I feel like most black boxes have 90 degree lenses on them

And if the trend continues with your data that would mean even less par. So is it better to run without lenses?
Yes, the light is dispersed into a larger area. Color mixing would be poor without this dispersion.
 

Pyrosteve

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I was curious about effect of lenses, so went into the lab to take a look. I used a 3-watt green LED (easy to see) and took a PAR measurement with no lens and measured the diameter of the light's footprint (PAR of 39 and a lighted circle measuring 46mm in diameter.) When I placed a 40-degree lens on the LED, the light footprints PAR fell to 11, and the illumination circle became indistinct but something on the order of 65mm. With a 60-degree lens, PAR fell to 8 and the light pattern larger but 'fuzzy.' Some of the PAR loss is undoubtedly due to absorption by the lens itself (not sure how much though.) It is obvious that blending of colors is increased by higher degree lenses. Maybe you've got all this figured out already but it did make me curious enough to spend a few minutes in the lab.

lens.jpg

Could the loss be from the diffuser pattern on those lens covers? The ones I have are clear.
 

Dana Riddle

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Could the loss be from the diffuser pattern on those lens covers? The ones I have are clear.
Wish I had some clear ones to check, without testing all I can do is speculate...
 

McPikie

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That's crazy. I always assume taking off the 90deg lenses would allow the colours to spread more evenly, but PAR would suffer as the light is not being "punched down" in the 90deg angle. I never assume without a lens the light would pretty much just go straight down.

Both my units have always had clear lenses, not diffused.
 

Dana Riddle

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A little more information. The green LED I used has a Viewing Angle of 5 degrees and, if I recall correctly, this would make the Beam Angle 10 degrees. This is due to the geometry of the internal doped reflector and would make the illuminated area small and bright. The lenses I used would disperse the light out to 40 or 60 degrees hence the illuminated area is large but less bright.
 

Flippers4pups

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That's crazy. I always assume taking off the 90deg lenses would allow the colours to spread more evenly, but PAR would suffer as the light is not being "punched down" in the 90deg angle. I never assume without a lens the light would pretty much just go straight down.

Both my units have always had clear lenses, not diffused.
Kinda makes sense. Light has to pass through the opaqueness of the plastic.
 

Pyrosteve

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A little more information. The green LED I used has a Viewing Angle of 5 degrees and, if I recall correctly, this would make the Beam Angle 10 degrees. This is due to the geometry of the internal doped reflector and would make the illuminated area small and bright. The lenses I used would disperse the light out to 40 or 60 degrees hence the illuminated area is large but less bright.
So the lenses disperse and not focus the beam? I wouldn't have thought that.
 

Dana Riddle

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So the lenses disperse and not focus the beam? I wouldn't have thought that.
I suppose focusing/dispersion of the light depends upon the Viewing Angle/Beam Angle of the LED. I'm *guessing* that a LED with a Viewing/Beam Angle of 40 degrees would be little impacted by a 40 degree lens (other than light attenuation by the lens itself.)
Is there an IES engineer in the house? ;)
 

Pyrosteve

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I suppose focusing/dispersion of the light depends upon the Viewing Angle/Beam Angle of the LED. I'm *guessing* that a LED with a Viewing/Beam Angle of 40 degrees would be little impacted by a 40 degree lens (other than light attenuation by the lens itself.)
Is there an IES engineer in the house? ;)
I'm curious to beam angle of the BB LEDs now. If by removing them completely if the beam is more or less dispersed. I was always under the assumption that is was more focused with any lens from reading previous posts. Maybe someone who has removed them can chime in?
 

Dana Riddle

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I'm curious to beam angle of the BB LEDs now. If by removing them completely if the beam is more or less dispersed. I was always under the assumption that is was more focused with any lens from reading previous posts. Maybe someone who has removed them can chime in?
If that info isn't readily available, remove the lens and measure the diameter of the lighted circle at a given distance, say, 6 inches. I think I have enough LEDs with different Beam Angles to compare.
 
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I just finished ordering my replacement diodes and they will be here in a couple weeks, so I'm now on the search for a recommended thermal paste for them. Anyone have a recommendation?
 

oreo5457

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Heatsink plaster or there is some made by Tian Mu.(or close)
Other than that thermal epoxy


Both of are basically thermally conductive silicone.

This isn't
glue
 
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