Does Ra = cri …?
Yes, CRI (or Ra) is the mean of R1-R8.
Wow, cri doesn’t even include the much talked about r9 … 
thanks! nice data capture
The zircon 803 has a 20% lumen penalty
the benefit is the DUV went negative… congrats on that
for reference, could you also post the same light without the -green filter?
what I like about the SST is the high R9… but I dont care for the green tint
the Lee filter keeps the high R9, and improves the tint… similar to the way slicing the dome of an LH351d does. But the LH351d is not a 90+ R9 CRI LED… and the green tint is as bad as the SST…
so I just ordered an SST light… though I may still mod to 219b, instead of using minus green filters.
That is why R9 is often mentioned separately.
R9-R12 are saturated colours and were all not part of CRI because CRI represents how natural colours look, not how saturated. They are important for good lighting though, and with leds the R9 (saturated red) is always the bottleneck so that is the one mentioned.
Okay that makes sense. I just thought it was discussed because it was always lacking…
With the Zircon 803 installed over the LH351Ds, R9 came in at 96 as you can see in the data above. That’s what I found most impressive since the LH351D typically comes in around R9 60-70.
I’ll retake measurements without the filter when I get a chance.
thanks for clarifying, I was confusing SST with LH351d
that IS a big jump in expected R9 for an LH351d,
great visuals, love your color graphs
| CCT | Duv | CRI | R9 | ||
| C8+ 351D 4000K | Without filter | 4200K | 0.0039 | 91 | 70 |
| C8+ 351D 4000K | With filter | 4060K | –0.0019 | 97 | 94 |
| D80v2 351D 4000K | Sliced | 3800K | 0.0012 | 93 | 77 |
Edit: added D80v2 with sliced LH351D
outstanding results, never expected R9 to go up by 34% from using an 80% transmissive pink filter. (minus green)
great info… you are the first to ever make me aware, of the strong positive effect of Lee Filters on R9.
thank you!
I generally see +10~20 pts of Ra with 803, 5~10 with 804.
This LH351D 4000k with +24pts is indeed significant but don’t expect it to always be that high.
Of course, it’s not really increasing the output of R9. Rather the filter is just reducing the output of all the other colors so they match the R9. Result is in a CRI test, R9 rates higher.
Filters do have some disadvantages.
- Expect output to drop significantly. Sometimes close to 20%.
- Expect color temperature to drop. Sometimes 500K or more.
Do the filters last forever (like for several years), or does their effectiveness change with time (even when not in use) or from using the light for hours at a time?
Doesn’t it also diffuse the beam some reducing the spot intensity?
Maybe i’m wrong but I always told myself that was the tradeoff I disliked the most. Narrow beam angles and reflectors generally have the most need for “adjustment” but also the biggest impact from filtering so it really is unfortunate if that is the case.
that makes sense…
apparently the CRI test does not show that reduction, it seems to rescale all the bars higher, not lower
that does not mean the comment is wrong, to me it means the CRI test is faulty. Because the test makes the filter look good on paper, but not in my reality.
from my personal experience with Lee minus green filters, they make the illuminated area Look like there is a Pink wash over everything … I really dont care for them, at all. They are, to me, just a cheap plastic toy to play with… I do not take them seriously, and would not want one on a light I consider valuable or special…
and yes, the lumen penalty is another reason I lose interest in filters…
They degrade over time.
Regular Lee filters degrade very fast. A few months at most in a high output light.
Lee Zircon filters are specially designed for LED use. They last much longer. They’ll still degrade, but I suspect it might be a few years before it is really noticeable.
Fortunately, the filters come in sheets. One sheet gives enough material for many filters.
The “pink wash” you mention is probably just the filter lowering the color temperature lowering to something below what you prefer.
If you prefer 4500K, you probably won’t be happy putting a filter on your 4500K LED. The filter might lower the color temperature below 4000K. Try starting with an LED with a cooler color temperature than you normally use. Then when you apply the filter, hopefully it will lower the color temperature to your preferred level.
Also, if things look TOO pink, the issue might be the filter lowered the output too far below the Black Body Line. In that case, perhaps the minus green filter you’re using is too strong. Try a weaker filter that does not remove as much green.
My main EDC is an FW1A that I installed an LH351D @ 4000k into as soon as I bought it. I would love to try this out for grins, how small a chunk can the Zircon filters be purchase in and do you just cut them with scissors?
Thanks Matt