XHP50 Lumen/Heat/CRI Questions

Hi Guys, I'm planning to buy a Zebralight, and I'm confused by the huge difference in lumens between the SC600w Mk IV Plus (XHP 50.2, 2300 lumens) and the SC600Fd/SC600Fc Mk IV Plus (XHP 50, 1816 lumens). As I understand it, the 2nd-gen XHP50 is supposed to be a modest improvement over the 1st gen -- but not 500 lumens' difference, right? Since all of these lumen numbers are so high, are they mainly hypothetical (like at the south pole) or not ANSI?

Do all three emitters create the same amount of heat initially, or does the 2300-lumen emitter create more? Basically, if the 2300-lumen emitter is much hotter initially, then the light would quickly step down, and after a few minutes, all three lights would be equally bright. So in that case, there would be almost no point to the 2300-lumen light (unless exploring the south pole). On the other hand, if the 2300 and 1816-lumen emitters create the same amount of heat initially, then the 2300-lumen version would always be brighter, even when they are stepped down. Could someone clarify?

Lastly, I see that the 4000K and 5000K emitters are both rated at 93-95 CRI, but is that realistic? Don't the warmer emitters have more of the frequencies that would produce a higher CRI? Also, the 4500K XHP 50.2 is rated at 80+, but does that actually mean about 80, or could it randomly be as high as 95?

Thanks in advance. I read a bunch of other threads, but still couldn't find what I was looking for. I understand tint color is a bit of a lottery, and that's okay. Are there any other caveats for these emitters/lights?

Hypo said:

Hi Guys, I'm planning to buy a Zebralight, and I'm confused by the huge difference in lumens between the SC600w Mk IV Plus (XHP 50.2, 2300 lumens) and the SC600Fd/SC600Fc Mk IV Plus (XHP 50, 1816 lumens). As I understand it, the 2nd-gen XHP50 is supposed to be a modest improvement over the 1st gen -- but not 500 lumens' difference, right? Since all of these lumen numbers are so high, are they mainly hypothetical (like at the south pole) or not ANSI?

Do all three emitters create the same amount of heat initially, or does the 2300-lumen emitter create more? Basically, if the 2300-lumen emitter is much hotter initially, then the light would quickly step down, and after a few minutes, all three lights would be equally bright. So in that case, there would be almost no point to the 2300-lumen light (unless exploring the south pole). On the other hand, if the 2300 and 1816-lumen emitters create the same amount of heat initially, then the 2300-lumen version would always be brighter, even when they are stepped down. Could someone clarify?

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I don't have the "c" version, but from what I understand, I think the LEDs are driven by the same driver, and so the "c" version produces more waste heat at the same lumen output. With both at max, they're using the same current, but the "w" version is producing a bit more light and a bit less heat. In other words, the "w" version should maintain a slightly higher output after PID settles the light down to a comfortable running temperature.

I could be wrong though, and someone with both versions could correct me.

Lastly, I see that the 4000K and 5000K emitters are both rated at 93-95 CRI, but is that realistic? Don't the warmer emitters have more of the frequencies that would produce a higher CRI?

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You're misunderstanding how the CRI is determined. It's based on whatever color temperature the light is operating at. So, a CRI of 100 with a temperature of 6500K will show a lot less red than a CRI of 100 at a temperature of 2500K. Even though they're both CRI 100, you have to factor in the color temperature to understand what colors will be emphasized.

Also, the 4500K XHP 50.2 is rated at 80+, but does that actually mean about 80, or could it randomly be as high as 95?

Thanks in advance. I read a bunch of other threads, but still couldn't find what I was looking for. I understand tint color is a bit of a lottery, and that's okay. Are there any other caveats for these emitters/lights?

Click to expand...

It's a bit random, but the "w" versions will definitely not be a CRI of 95. Their tint is still very nice, though colors will be a bit better with the high CRI emitters.

The only other thing people complain about is tint shift across the beam, especially with the regular domed emitters (unlike the HI versions). I haven't found it too annoying, though. It's mainly a white-wall hunting thing.

Two things right off the bat. The 50.2 is an 80 CRI emitter so it will be binned higher so there some lumens. The F lights are also floody so there is some more lumen loss.

The MK4 C and D headlamps are 50.2 as well.

I'd say they should both draw about the same heat at turbo levels. The 80 cri emitter found in the Plus will have more lumen efficacy than the 90+ emitters found in those high cri headlamps.

I don't have the "c" version, but from what I understand, I think the LEDs are driven by the same driver, and so the "c" version produces more waste heat at the same lumen output. With both at max, they're using the same current, but the "w" version is producing a bit more light and a bit less heat. In other words, the "w" version should maintain a slightly higher output after PID settles the light down to a comfortable running temperature.

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WalkIntoTheLight, that helps a lot, thanks for such a detailed reply. By the way, I watched your YouTube video on the Zebralights, much appreciated.

You're misunderstanding how the CRI is determined. It's based on whatever color temperature the light is operating at. So, a CRI of 100 with a temperature of 6500K will show a lot less red than a CRI of 100 at a temperature of 2500K. Even though they're both CRI 100, you have to factor in the color temperature to understand what colors will be emphasized.

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Yeah, I misunderstood. I did some reading, and as opposed to what I'd assumed, the CRI rating doesn't definitively say how naturally colors will appear in the emitted light. And the methods for choosing a reference, measuring, and calculating the CRI seem to all be flawed. In your example, if a light at 6500K can have a CRI of 100 and that doesn't mean that all visible frequencies appear natural (as they would in actual daylight), then it's hard to know how this rating is useful. And if I understand correctly, I can't even say that 90 is always better than 80.

The MK4 C and D headlamps are 50.2 as well.

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Twistedraven, I took the information from their website. Have you confirmed that they're 50.2? Does that mean the lumen/CRI numbers are out of date?

I haven't opened these lights up myself to confirm the emitter, but this is straight from Zebralight's site:



H600FC MK4, H600FD MK4, H600FC MK4, H604D, SC600w MK4 Plus are all 50.2.

Hypo said:

Yeah, I misunderstood. I did some reading, and as opposed to what I'd assumed, the CRI rating doesn't definitively say how naturally colors will appear in the emitted light. And the methods for choosing a reference, measuring, and calculating the CRI seem to all be flawed. In your example, if a light at 6500K can have a CRI of 100 and that doesn't mean that all visible frequencies appear natural (as they would in actual daylight), then it's hard to know how this rating is useful. And if I understand correctly, I can't even say that 90 is always better than 80.

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CRI is not really a great method of determining a light that will give accurate color rendition. But, it's better than nothing. Personally, I usually prefer a warm tint with a modest CRI, than a cool tint with a high CRI. For example, I like a Cree LED 4000K tint with a CRI of 75 or 80, more than I like a Nichia 219 LED with a high 93 CRI at 5000K. The high CRI 5000K does give better color separation, but I prefer the warmer hues and better reds and browns from the 4000K light. That said, I think most people here would prefer a high CRI 5000K tint.

You'll just have to experiment and see what you like best. I recall when LED Maglites first came out, I thought they were great. :sick2:

Hypo said:

Twistedraven, I took the information from their website. Have you confirmed that they're 50.2? Does that mean the lumen/CRI numbers are out of date?

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Twistedraven is talking about the H600 headlamps, which use XHP50.2. The SC600Fd/SC600Fc Mk IV you're asking about use XHP50.

WalkIntoTheLight, thanks again for explaining. I think I'll go with the 4500K XHP50.2 version, and I also believe that the warmer light will make up for lost color separation.

Jay30, thanks for clarifying.