What happens to Spectrum when we dim our lights?

jonsnow399

Well-Known Member
Ushio pro plus at 600 and 1100W. i tried to do 1100 at a slightly greater distance to get the light intensity equal

looks like only a very slight spectrum shift if any
This info if correct (and I don't see any reason to doubt it) puts to rest the idea that dimming a hid changes spectrum.
 

wietefras

Well-Known Member
This info if correct (and I don't see any reason to doubt it) puts to rest the idea that dimming a hid changes spectrum.
Well I saw a slightly bigger change with A Gavita Pro 1000W DE, but the spectral shift is insignificant yes.

If anything, the bigger issue is the loss in efficacy when dimming a HPS bulb that much.
 

jonsnow399

Well-Known Member
Well I saw a slightly bigger change with A Gavita Pro 1000W DE, but the spectral shift is insignificant yes.

If anything, the bigger issue is the loss in efficacy when dimming a HPS bulb that much.
gavita claims that their 750 bulb can be dimmed to 600 watts with no loss of efficacy.
 

wietefras

Well-Known Member
gavita claims that their 750 bulb can be dimmed to 600 watts with no loss of efficacy.
Yes, but is that the same as 1000W to 600W?

Dim that 750W bulb to 450W and the efficacy will have dropped.

They also don't say that it's with "no loss of efficacy", but that it's still near 2,0umol/s/W at 600W. Of course it will still be slightly lower than at 750W.
 

jonsnow399

Well-Known Member
Yes, but is that the same as 1000W to 600W?

Dim that 750W bulb to 450W and the efficacy will have dropped.

They also don't say that it's with "no loss of efficacy", but that it's still near 2,0umol/s/W at 600W. Of course it will still be slightly lower than at 750W.
"We named it 6/750 DE FLEX because it is as efficient running on 600W as it is on 750W." Thats their advertising .
 

wietefras

Well-Known Member
"We named it 6/750 DE FLEX because it is as efficient running on 600W as it is on 750W." Thats their advertising .
Ah their marketing says it's so. Then it must be true :roll:

Just like all those blurple claims must be true?

Besides, they blatantly lie about the output of the "lamp" as well. It's not emitting 2umol/s/W. Probably more like 1.6umol/s/W.

Again, their actual specs don't claim it's at the same efficiency. Just that it's around this supposed 2umol/s/W both at 600W and 750W, but their 1000W fixture is also slightly more efficient at 1150W over 1000W It's obvious that the same goes for their 750W fixture. Going by the difference on the 1000W model it will be a 4% difference in efficacy between 600W and 825W. While at both wattage's it would still be rounded to 2.0umol/s/W for the bare bulb measurement.

So even if the specs and marketing are not 100% incorrect, 4% is still a decent difference.
 

a mongo frog

Well-Known Member
Gavita's do change spectrum visibly when you dim them. The HPS light does turn noticeably more blue if you dim them more than just a bit.
Ive found this to be true, but the complete opposite. Im not sure if your mean Gavita or if your talking DE bulbs, but i noticed on the Green power bulbs from Phillips powered by the nanolux ballasts that at the 1000 watt setting is throwing more of a red color and the 1200 watt setting in way more white maybe the blue you speak of.
What bulb were you running in your Gavita?
 

CobKits

Well-Known Member
a different question since were completely off topic anyway

how many different ways are there to dim HID and is it possible that some ballasts shift spectrum and others dont?
 

Evil-Mobo

Well-Known Member
a different question since were completely off topic anyway

how many different ways are there to dim HID and is it possible that some ballasts shift spectrum and others dont?
I would like to know this as well if anyone has an answer based on solid info. My ballasts are not dimmable and all I use for HID is Hortilux stuff so..........

If I had the height thought the Gavita's would be a no brainer for what the fixture's cost but that's not the case for me
 

PSUAGRO.

Well-Known Member
I would like to know this as well if anyone has an answer based on solid info. My ballasts are not dimmable and all I use for HID is Hortilux stuff so..........

If I had the height thought the Gavita's would be a no brainer for what the fixture's cost but that's not the case for me
Can run that ac/dc hood with de bulbs for height restricted, probably know that:)..................hid, led are two different animals when it comes to dimming
 
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CobKits

Well-Known Member
fwiw the DE i measured was in an ACDE. that hood is da bomb - such great coverage and you dont need 9 ft ceilings to make DE work
 

CobKits

Well-Known Member
there are good par maps on growershouse.com i was running 2 of them at 30-36" in a 5x9 tent
 

jonsnow399

Well-Known Member
Ah their marketing says it's so. Then it must be true :roll:

Just like all those blurple claims must be true?

Besides, they blatantly lie about the output of the "lamp" as well. It's not emitting 2umol/s/W. Probably more like 1.6umol/s/W.

Again, their actual specs don't claim it's at the same efficiency. Just that it's around this supposed 2umol/s/W both at 600W and 750W, but their 1000W fixture is also slightly more efficient at 1150W over 1000W It's obvious that the same goes for their 750W fixture. Going by the difference on the 1000W model it will be a 4% difference in efficacy between 600W and 825W. While at both wattage's it would still be rounded to 2.0umol/s/W for the bare bulb measurement.

So even if the specs and marketing are not 100% incorrect, 4% is still a decent difference.
No I don't necessarily believe anything a marketing or sales rep says that's why I'm asking here.
 
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