I also used my camera, and it does see some kind of banding on my FWAA, and on my Jetbeam and Niteye magnetic rotaries. Im reassured by the added info provided by the Opple flicker risk assessment:
Jon, a couple of questions… I have been testing the lowest end of several lights for consistency. I have a pair of Hank’s lights, D4V2 and KR4, both have SST-20 4000k installed. The KR4 are FD2 and the D4V2 are maybe FA3. I have both set on 2/150 and took readings by covering the window with the head of the light. Both readings are very close, around 288 lux and the chromacity is very good on both lights, right at or just a tiny bit below the BBL and yest the look that good to they eye.
I use this calcualtor:
I converted the surface area of the sensor circle to feet squared:
0.002506944
Input my lux reading of 288.
Results are .067 lumens. This seems to low to me, what am I doing wrong? Any ideas?
> Results are .067 lumens. This seems to low to me, what am I doing wrong? Any ideas?
I dont have those lights nor LEDs, and no experience calculating lumens from Lux…
Im guessing the area and distance calculations are introducing errors.
fwiw, the lowest output on my FWAA is 0.1 lumens at 1/150 w sw35, so your calculation of 0.07 lumens at 2/150 does seem lower than expected.
My only suggestions would be to test level 1/150, move the light away from the sensor, and recalculate with the new distance… see if the lumen result is more realistic…
I'm having a great time testing every light in my house for CCT and CRI. This thing is great! It made me realize I need to upgrade a few of my light bulbs. Older CFL's are pretty bad with CRI.
You can’t convert lux to lumens by pointing the light at the sensor. Even if you place it very close, there will be too much loss to get an accurate calculation. You would need some kind of integrating device.
still really happy w my Opple, found a new application
I wanted to see the effect on CRI, of blending sw30 and sw45k… Im pleased… blended CRI seems to be the average (with significantly lower DUV at 3700K, than a single source sw35):
.
and another use for the Opple, compare the effect of AR coated glass placed on top of a sapphire lens, to see if there is a significant change in Tint…
The claim is that the purple AR coating will make the Tint Greener… it does, but I dont think the amount of change is significant… it raised DUV by 0.0004. I do not perceive that as a Visible Change. The LED is sw45K:
.
also tested a blue reflective lens… zero change in Tint DUV:
.
.
so, for people wondering if AR coating is a primary cause of green Tint, or wondering if removing AR coating will reduce green Tint … Nope… removing AR coating will not fix green Tint…
Let me counter this with some measurements from my spectrometer.
This is a D80v2 with 219b sw30 and the factory green AR coat glass.
Here is the same light on the same mode but with a Convoy C8 purple AR coat glass held in front of the light. The tint change is clearly visible to the eye.
The Opple is a neat and useful device, but it’s not a scientific instrument. It simply isn’t accurate enough to measure small tint changes like this. Just holding it at a different angle or distance from the light will make the measurement deviate significantly. It’s still great as long as you understand its limitations.
Yes. I think CCT measurements are ok for a good guessing of the LED version. Time signal is also very useful, but the CIE coordinates are not reliable and the Ra is nearly always quite optimistic, probably deliberately to always get a 100 score for incans.
What’s missing is a comparison of the luxmeter with a reference instrument. I am really interested how good it is.
I believe there are different AR coatings and some of them could have the same reflection color.
I have noticed this as well. All of my very high CRI lights measure 100 CRI with the Opple.
Through my own measurements I’ve found that all of the blue/purple AR coats that I’ve tested slightly increase duv and the green ones (seem to be rarer) tend to decrease duv. I haven’t tested any clear/colorless AR coating.
If you think about it, it makes sense. If the reflections appear green, that means more green light is bouncing off the surface and not being passed through the material, which will make the remaining light that does pass through have less intensity in the green wavelengths (lower duv).
+0.0020 is definitely much larger than what Im getting with the rose reflective AR lens on my RRT-01 (changed duv +0.0004) and blue reflecting V10R (0.0000 change in duv)
I agree the Opple is not a super sensitive instrument. otoh, it gives me a reference that my eyes and words alone, cannot communicate as effectively.
I see now why people say Simons AR lenses have a big impact on Tint… thanks for expanding my education.
Im not sure the Opple would fail to detect the difference in DUV created by the Convoy lens, as I do not have any Convoy lights
for the side by side tests that Im doing, I feel the Opple gives enough info to Compare, even if the absolute values may differ from other instruments… not sure
> All of my very high CRI lights measure 100 CRI with the Opple.
the CRI readings I get are not 100, it gives better detail, as you can see in this composite of 2 lights, separate, and blended:
.
So, since I hear that Simons lenses have +0.0020 DUV impact, can we say it is due to the quality of the glass, or do we know it is from the characteristics, thickness, composition, color, of the AR coating?
I dont think the blue reflection alone, is a reliable predictor of +0.0020 DUV increase…
has anyone tested a Convoy lens w AR removed?
has anyone confirmed that the Convoy AR is the culprit of the DUV increase, and not the glass itself?
I took readings again of the D80v2 with and without the Convoy AR coated glass, but this time with the Opple.
L: D80v2 219b sw30
R: D80v2 219b sw30 + Convoy AR coated glass
From this we can infer:
- The Opple does not provide accurate quantitative readings for duv (spectrometer measurements for duv were –0.00207 & –0.00004, respectively) This comes as no surprise as it isn’t really intended to provide this information.
- The Opple can provide reasonably accurate qualitative comparisons for duv given that it is the same emitter which is being compared against itself
Here is a comparison of measurements of my Acebeam E70 with GT-FC40 4500K from my spectrometer and from the Opple.
We can see that with the D80v2, the Opple’s CIE coordinates give us a duv that is higher than the spectrometer’s measurement, yet with the E70, it is significantly lower. This means that the qualitative duv comparisons between different emitters will not be accurate with the Opple.
You can also see an example here of the Opple giving a 100 CRI reading for a very high CRI LED.
Now don’t get me wrong, I’m not saying the Opple is bad. I think it’s a great piece of kit, especially for a 30USD price tag. I intend to keep and use mine despite the fact that I have a spectrometer. But it isn’t going to give you readings that are as accurate as what you’ll get from an actual spectrometer. The Opple probably just has a cheap CMOS sensor in it. A spectrometer works in a fundamentally different way to achieve its measurements. So, while your duv calculations can be useful for comparisons, you should take the numbers with a grain of salt.
I have found, like many others that it is not perfect… But, it is a better way of quantifying light than the SWAG method and does not cost hundreds of dollars.
100 CRI, the only time I have seen that reading is out in full sun. The CRI numbers I have gotten across maybe 50 lights I have tested so far seem to be very reliable. I have tested many variations and ages of Nichia leds, 3 samples of FC40’s, LH351’s, SST-20’s and a few other emitters. I think this is the function I like the most. It was most interesting to look at my selections of XP-L Hi 5A2 and 5A3 emitters and a few XP-l HD and XHP-50.2’s.
Rayoui
thanks very much for the reality check
> D80v2 with 219b sw30 and the factory green AR coat glass.
DUV –0.0021
> Here is the same light on the same mode but with a Convoy C8 purple AR coat glass held in front of the light.
DUV 0.0000
change caused by convoy lens +0.0021
===
opple data
> D80v2 219b sw30
DUV 0.000
R: D80v2 219b sw30 + Convoy AR coated
DUV 0.0011
change caused by convoy lens based on Opple +0.0011
===
data observation
spectrometer reads –0.0021 (lower) than Opple, on D80V2
spectrometer reads –0.0011 (lower) than Opple w convoy lens
spectrometer calculates DUV difference 0.0010 higher than Opple
I’m considering getting one. I’m assuming it is made and designed to just take light samples from various places in rooms and so forth. So my question is, are you guys measuring things in totally dark rooms and from what distances with these flashlights? Somebody above already pointed out that they’re getting different readings depending on the distance. So publishing all this data without everybody on the same page as far as darkness and or distance, I don’t know if it’s useful. Especially when we’re starting to add in two stacked different colored AR coated lenses. Do we know if it makes a difference on which side of the AR coating is facing down or up? There are a lot of variables here.
More Opple data
testing stock lens of FWAA impact on DUV (it has a pink AR)
FWAA with uncoated sapphire lens
3x 3500k 219B
DUV –0.0005
with original fwaa lens in front
DUV –0.0001
net change, not significant… +0.0004
First, I measure in the dark, with the light that has an uncoated sapphire lens, 6” from the sensor…
next without moving the light, I place the test lens against the bezel and take another reading…
it seems the absolute values may not be the same as on a more expensive and calibrated instrument
however, I think the comparison of the same light, with and without an AR lens, might be giving useful data… for me to compare with my own light and lenses
I do also use the Opple to test LED light bulbs in my house, for flicker, and DUV
and also to compare the DUV effect of blending two beams…
and it also lets me compare the DUV of different LEDs
I have several different sw45k for example, and some are much more pink than others
.
the Opple DUV calculation tracks what I see with my eyes… the most pink has the lowest DUV
when comparing multiple lights, first I start by setting them to the same lumen output, on a separate meter. Then using the opple I set the light distance to produce similar lux on the opple,
and then I use the xy coordinates to calculate DUV online
I guess I’m going to have to get one. I’m wondering if the numbers are going to change at 6 feet or 60 ft were we are actually looking at things rather than 6”. Also spot verses spill. Without the AR coating output goes down but I forgot by how much. And I’m sure that’s not a static number. Again more variables.
I dont use those distances
but, if you do, just be consistent
most of my tests are at relatively low output of about 20 lumens… Im not testing throwers outdoors… lol
I find that the numbers seem to be most consistent when I pick the distance based upon the mode of the light. I cannot isolate 6 or 60 feet from outside interference, so I tend to pick a number in lux and generally target that amount of light hitting the sensor for each mode governed by distance.
I do the same
when making comparisons I try to approximately match the Lux of each light on the Opple…
I aim for about 20,000 Lux for each Opple sample…
sometimes I fine tune the Lux reading, by moving the light a bit closer or further… from the sensor