Barrel of Monkeys 
https://www.amazon.com/Winning-Moves-Games-1246-Classic/dp/B0B5FBQ7TH/
just about anything is more fun than a barrel of monkeys… 
I am possibly one of those annoying customer types who wouldn’t forgive and forget. Sent message to Opple about what they should do with next gen Light Master, and surprised to see that they actually replied. So it seems next gen Light Master Pro is for real, with USB-C, let’s see if they will have R9 and calculated Duv also.
Their email if you want to send your input:
“If you have some advice, or request about 4th generation, please send Email to us.
Thank you for your supports of Light Master.
Email Address: opplelightmaster@outlook.com ”
Thank you for your support of OPPLE.
We’ve give this suggest to our Product Manager.
USB-C will be added in 4th Light Master
This guy compares the pro to some VERY expensive light meters. He does not cover duv other than to point out the chart on the app.
Hi,
I just bought an Opple Light Master G3 to “measure” my light collection and to check my led strips.
But the latter doesn’t seem to be possible with this device.
I’ve got a cheap Onvis RGB led strip. On white or yellow a orange S2+ looks like red,
on yellow a purple S2+ is something like brown or a S21 is light brown.
This led strip doesn’t have an additional white LED. On a more expensive one with a
white LED the colours are correct, orange is orange and purple is purple.
The Opple device doesn’t even detect any light source if I switch the cheap RGB led strip to white,
all values stay empty and on yellow, blue and most other colours Ra is 100.
White on the more expensive RGBW led strip is detected, but Ra is 100 in most colour cases, too.
There seem to be issues with pure light colours.
Blue (CSLNM1.14) has Ra 100 and CCT 1637K, but x=0.1518 y=0.0337 u=0.1958 and v=0.0651 seems to fit.
Red (SST20-DR) shows Ra - CCT 5861 and x=0.6001 y=0.2561 u=0.4926 v=0.3153
I think these are software bugs, since the graph looks fine in most cases. Except the RGB white light.
But I don’t know how trustworthy the device and software is.
Sorry, English is not my native language.
The Opple cannot measure lightsources with non-contiguous spectrum. It has only filters for six wavelengths and estimates the distribution of the light spectrum via these six colors. This will also result in wrong results for light with small bandwidth.
Hi cannga, this is mine:
519A 4500K Convoy s2+
5/5 level
Thanks. Yeah in the negative low teens is what I am getting.
The other odd thing is my 519a 4500k has always had CCT measured lower than specs. It was around 4100k at one time, but now it’s reading 3900k. Maybe the heat from all the Turbo run-down I’ve been doing? Whatever it is, it’s been much lower than 4500k.
Yes, mine is 4160CCT at start, also.
.
Remember these specs from emitter manufacturers are for the bare emitter at whichever rated currents are specified in their data sheets. With a bodgy tool like Opple we can only do so much, but if you’re concerned that you’re getting different results, try measuring the bare emitter and see what you get (it would be best to compare now vs. then-when-new of course). If you have a power supply that would be even better but maybe with your driver you can try to pick a mode that approximates the data sheet choice.
Usually won’t see any drastic reduction in output with most emitters unless you’re really pushing them above the rise but that depends on heat dissipation too. Nichias have always been a little more susceptible to it compared to what we’ve seen with most Cree and Luminus but so far the 519A seems pretty robust. Make sure contacts are clean and in good shape, too…doesn’t take much to get enough resistance to affect current delivery a little.
Thanks but all my other LED’s (Getian, Nichia, etc., etc.) measure within reasonable range with the “bodgy” (but “invaluable”) 
Opple. Only 519a is off, interestingly IIRC often on the low side, and I believe this has been observed by others, not just me.
Of note Convoy (and maybe others) sometimes list a range for CCT specs for some of the flashlights/LEDs, eg 4000-4500k, so I understand spec variations. But my Nichia lights (219c, 219b, B35AM) in particular have been close to spec, and I don’t recall ever listed in a range. That’s why I made that remark above. The case of 519a CCT (from Convoy?) is interesting. I actually have brought it up to his attention and even asked if he could personally check the next 519a light I buy from him 
.
Some examples (@Argo note our 519a CCT and Duv match well):
When ranges are listed it’s because that’s the binning that has been purchased (and some are not available in tighter binning at all). Nichia tends to be more on target but honestly I’ve never looked that closely at that part of their data sheets (i.e. I don’t know if they have an “easy white” setup like Cree, etc, but that is a popular and cost-saving option for manufacturers to take advantage of rather than specifying a tighter single bin, especially if they are needing to buy in quantity). But all that is just bare emitter, as sold and usually as advertised…once it becomes a light with a driver and optics it’s all different and many variables come in to play. If you test the finished light and you see changes in output somewhere, it’s hard to narrow it down even if you had an as-new baseline comparison. Coupled with the handy-but-bodgy capability of the Opple sensor and its known shortcomings it’s just hard to chase any accurate conclusions sometimes. Both of my Opples (II and III) were low in CCT and they also varied enough so as not to be considered reliable, but “good enough” in terms of just knowing what range the emitter temp is in. I held off on buying the Hopoocolor until the world settles down a little but that’s something worthy of consideration if you want to get into measurements (sphere, decent meter, power supply…all that can be had for not too much money so it’s the upgrade-from-opple that is the cost outlay and it’s not necessary to go with the expensive photography/cinema models or something lab-worthy). Sorry if any of this sounds repetitious (I’ve probably posted similar before). Not sure if you’re making use of the manufacturer data sheets and grasping the foundations from the bottom up rather than trying to learn all that from the top down, so to speak. It does sound like an investment in a capable measuring tool would be right up your alley, though, and if you ever wanted to do emitter tests it would be awesome for everyone…we seem to have lost most of our traditional reliable testers and their methods/equipment.
I think if you truly want accuracy it would have to be something calibrated against reference, which the Hopoocolor is not. There is really no end to the craziness if you want accuracy. I am just not nutty enough to spend that kind of money.
The value of measuring device could also be in comparison of changes, not just absolute accuracy. But really not the place or the time to discuss this complicated topic or why Opple is more than good enough for me. As we are in BUDGET light forum, not measuring dose of life saving medication, it’s crazy to me to spend more (unless you are in the business for example).
PS Do we need to go through this every time I ask a question on this thread? Could we please just settle on “I’m happy with my Opple since the numbers are accurate enough for me, you are not.”? (At work we would say “could you please not try to help me.” 
)
Well, there’s bodgy, there’s accurate-enough, and there’s reference grade lab equipment. Hopoocolor is pretty darn capable and not terribly expensive and doesn’t have all the cinematic stuff that we don’t need. Didn’t think you were nutty, just that as interested as you seem with the numbers and comparisons that you might want to pursue something that can give them to you better. Flashlights and emitters are in kind of a different place than where most of these photometers and such are, which is why we’ve always found ourselves in the middleground in terms of accuracy, and the Opple certainly didn’t solve that where it matters (duv, mostly). Gen 4 may be a better unit, but we’ll have to see…and if so, whether “better” in this context is really better or not, keeping in mind that their device is really not intended for concentrated beams but rather open air lighting in casual and office lighting environments.
DUV calculation can be done in Excel. The calculation is not complicated and can be done directly in Excel.
Put x value in A2 and y in B2.
Put the following duv formula in C2
=SQRT(((4A2)/(-2A2+12B2+3)-0.292)^2+((6B2)/(-2A2+12B2+3)-0.24)^2)-(-0.00616793ACOS((((4A2)/(-2A2+12B2+3)-0.292))/(SQRT(((4A2)/(-2A2+12B2+3)-0.292)^2+((6B2)/(-2A2+12B2+3)-0.24)^2)))^6+0.0893944ACOS((((4A2)/(-2A2+12B2+3)-0.292))/(SQRT(((4A2)/(-2A2+12B2+3)-0.292)^2+((6B2)/(-2A2+12B2+3)-0.24)^2)))^5-0.5179722ACOS((((4A2)/(-2A2+12B2+3)-0.292))/(SQRT(((4A2)/(-2A2+12B2+3)-0.292)^2+((6B2)/(-2A2+12B2+3)-0.24)^2)))^4+1.5317403ACOS((((4A2)/(-2A2+12B2+3)-0.292))/(SQRT(((4A2)/(-2A2+12B2+3)-0.292)^2+((6B2)/(-2A2+12B2+3)-0.24)^2)))^3-2.4243787ACOS((((4A2)/(-2A2+12B2+3)-0.292))/(SQRT(((4A2)/(-2A2+12B2+3)-0.292)^2+((6B2)/(-2A2+12B2+3)-0.24)^2)))^2+1.925865ACOS((((4A2)/(-2A2+12B2+3)-0.292))/(SQRT(((4A2)/(-2A2+12B2+3)-0.292)^2+((6B2)/(-2A2+12B2+3)-0.24)^2)))-0.471106)
I know the formula looks ugly and not elegant,but it works well.
Once you verify the calculation, you can copy and paste the formula to next to the columns of cie x and y.
The formula is direct conversion of the code from waveformlighting.com website.
Calculate Duv from CIE 1931 xy coordinates | Waveform Lighting
u = (4x) / (-2x + 12y + 3);
v = (6y) / (-2x + 12y + 3);
k6 =-0.00616793;
k5 =0.0893944;
k4 =-0.5179722;
k3 =1.5317403;
k2 =-2.4243787;
k1 =1.925865;
k0 =-0.471106;
Lfp = Math.sqrt(Math.pow((u - 0.292),2)+Math.pow((v-0.24),2));
a = Math.acos((u-0.292)/Lfp);
Lbb = k6Math.pow(a,6) + k5Math.pow(a,5) + k4Math.pow(a,4) + k3Math.pow(a,3) + k2Math.pow(a,2) + k1a+k0;
Duv = Lfp - Lbb;
Here are my measurements with Opple 3 and calculated DUV using the Excel formula.
!https://i.imgur.com/JvdHonC.png!
:+1:
BTW, I’m using a spreadsheet from TI to draw diagrams:
It’s a bit complicated finding the correct entry cells for CIE coordinates, and the diagram needs some work to make it nicer, but it works well. Maybe there’s better software, don’t know.
Cannga, can do, will do…in fact I’ll just unsub from this thread. By the way, when you constantly go back and edit posts, nobody knows unless they happen to catch it or someone brings it to their attention. You edited pretty heavily on that one. Makes it difficult for forum conversations and future reference. Enjoy your endeavours with opple and learning about lights.
I think I’m gonna wait for the 4th gen device. Micro USB is unacceptable for me in 2022. I sent them the following email:
Add these features for the 4th gen Light Master device:
- Replaceable AA battery (If you don’t offer a replaceable battery, then give us a bigger integrated battery and a USB-C port)
- Duv value visible in the app
- R9 value visible in the app
- Make the sensors more accurate
- Keep the price low (about 30 USD)