Help!!! Best device to get? Light temperature testing.

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CollectEverything
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Help!!! Best device to get? Light temperature testing.

I want to test for two reasons. A) So I know what temperature my favorite lights really are and and B)To confirm if I receive the right emitters.

This is prompted in part by the arrival of a new KR4 flashlight from Hank. I mentioned that I wanted a KR4 but would wait for the 5000k XPL-Hi emitters to be back in stock. He said he though he had some 5000k XPL-HI emitters left (unadvertised on the site) and told me to place the order and send an email. The light arrived and to me it appears quite cold. I estimate 6000k or higher. :/

So what measuring tool is the best bang for buck out there?

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Edited by: CollectEverything on 09/13/2021 - 16:03
raccoon city
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Ooh...

Good question!  :BEER:

Lightbringer
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It ain’t as easy as it sounds. With lots of LEDs and color-shifting, especially in reflector-based lights, the hotspot can be overly yellow, and the spill overly blue, ie, the classic fried-egg beam.

The 4C is one of my faves behind a TIR lens with good color-mixing, but for the longest time in my reflectored S2+es, it looked waaaaaaay too warm.

When I did ceiling-bounce to light up a dark room, it looked quite nice. And that’s when I realised that it was mixing hotspot and spill off the ceiling to come up with the proper ~4500K mixed color.

Some people do measure various points in the beam, with little ‘X’es and the CT to match, but they might do it off a camera setup or something, no idea.

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CollectEverything
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Lightbringer wrote:
It ain’t as easy as it sounds. With lots of LEDs and color-shifting, especially in reflector-based lights, the hotspot can be overly yellow, and the spill overly blue, ie, the classic fried-egg beam.

The 4C is one of my faves behind a TIR lens with good color-mixing, but for the longest time in my reflectored S2+es, it looked waaaaaaay too warm.

When I did ceiling-bounce to light up a dark room, it looked quite nice. And that’s when I realised that it was mixing hotspot and spill off the ceiling to come up with the proper ~4500K mixed color.

Some people do measure various points in the beam, with little ‘X’es and the CT to match, but they might do it off a camera setup or something, no idea.


Do any of those people hang out here on BLF?

Everything you say makes sense. The XPL-Hi emitters are pretty uniform though. I’d think even a novice like myself could figure out how to measure the temperature given the right gear.

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Collection: TN42, TN40S, Catapult V6, SP36 BLF, sc700d, sc64c LE, D4V2 CuZn, D4V2 CuTi, D4V2 Al x2, KR4 Al x2
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Lightbringer
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Yeh, forgot who, though.

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Correllux
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I know very little about this but I sure respect the guys who have inve$ted in the equipment and have the know-how to use and understand it.  Earlier this year Simon showed one of these in use...if not this exact model it was very similar.  Basically it's the cheapest option that has a chance of being worth a hoot.  Pricing goes up exponentially, fast. 

https://www.aliexpress.com/item/10000034458900.html

Most of the "real" stuff seems to be $2500 or triple that although I saw some kind of student versions or something in the $1500 range. 

ChibiM
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I'm in the same boat. Have been looking around for quite some time, and as Correlux pointed out, that's about the cheapest option you have for a handheld device measuring CCT and CRI. 

If you're purely looking at CCT, and not CRI, then maybe you could look at the following 'old' tool, named a Gossen Sixticolor 

It's a device for photographers from the 70's I think. It may not be perfect or too accurate, but it's a cheap way to start. 

Front and back

thefreeman
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Copied from a previous comment of mine :

Quote:

Maukka uses a X-rite i1Pro, I have a i1 studio and that also works, they have the same capabilities regarding spectrum power distribution acquisition.
The i1pro can be used with Babelcolor CT&A (paid) to display the chromacity, CRI, TM-30, with nice reports (see Maukka’s threads)
Both can be used with Argyll CMS (free, command line tool) which also displays this info, though not nice reports, but the spectrum data can be loaded into Osram Color Calculator (free) which displays all kind of info and can make nice TM-30 reports like this .
Alternatively there is a paid Argyll pro Android app which is well, more mobile than a PC. The issue with it is that you can’t export the SPD data, Contactcr uses it .

So this is for measuring CCT and color rendition, I bought my i1 studio 340€, less expensive than the Aliexpress spectrometer linked by Correllux, it’s not handled though, but can sort of be with a smartphone and the paid Argyll Pro app. i1 pro and colormunki photo/i1 studio can sometimes be found second hand for less.

If color rendition is not needed then a colorimeter like eye-one display Pro (see Argyll CMS compatibility list ) can do and will be less expensive.

Somebody mentionned Opple products : https://budgetlightforum.com/comment/1797519#comment-1797519
Don’t know what they’re worth.

DIY spectrometers with a webcam and CD might be good enough to differentiate between two LEDs CCT.

Smartphone apps are wildly inconsistent.

ChibiM
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I just ordered the Opple Light Master III 

Let's see how well it works. 

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ChibiM wrote:
I just ordered the Opple Light Master III

congratulations Thumbs Up

I look forward to your impressions

I cant find it on Amazon in USA, only on a site called eibabo, that seems sketchy

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I do as well… trying to find a place in the US to get it.

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

Correllux
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That's really interesting about the Gossen...never heard of those!  Thanks for sharing that, ChibiM.  Have no idea how those could work but I'm going to start googling to see what I can learn.  Sometimes "old tech" amazes me in the ways that people came up with solutions and the theories behind them.  We are so used to electronic gizmos that do everything imaginable that most of us can hardly even to the necessary math and thinking to start the walk to the solutions in a more basic way. 

CollectEverything
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Thanks for all the info everyone! I’m starting to think I should just sell the KR4 with the not-5000k emitters though. What is the point in measuring it? The bottom line is that it doesn’t look like my other 5000k lights and measuring it won’t change that.

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Collection: TN42, TN40S, Catapult V6, SP36 BLF, sc700d, sc64c LE, D4V2 CuZn, D4V2 CuTi, D4V2 Al x2, KR4 Al x2
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ChibiM
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Hmm. so far, I like it. 

I only played with it for less than 30 minutes, and here are some of my measurements against the Maukka calibration lights I have. 

. . Light: 2107 Light: 2007
CCT Maukka 5933 3878
CCT Opple 5726 3904
Ra Maukka 79.1 94.7
Ra Opple 77.7 96.6

As far as I'm concerned, I'm pretty satisfied with this. 

I pointed the light in my integrating spheres and measured these 2 lights I have from Maukka. 

I didn't point directly to the sensor. 

 

For me, (for my reviews) the most important thing is to show in what CCT range a light is. Even if it's off by 10+%, I'm okay with that. It's more to show if it's 6500-7000K or 5000-5500K. 

I'm not 100% sure how accurate the CRI measurement is. I just tested another light with an SST70 and got about CRI64... 

Mike C
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Where did you order it from? Opple home page doesn’t seem to take orders, some other sites appear to have it though.

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ChibiM wrote:

Hmm. so far, I like it. 


I only played with it for less than 30 minutes, and here are some of my measurements against the Maukka calibration lights I have. 



































. . Light: 2107 Light: 2007
CCT Maukka 5933 3878
CCT Opple 5726 3904
Ra Maukka 79.1 94.7
Ra Opple 77.7 96.6

As far as I’m concerned, I’m pretty satisfied with this. 


I pointed the light in my integrating spheres and measured these 2 lights I have from Maukka. 


I didn’t point directly to the sensor. 


 


For me, (for my reviews) the most important thing is to show in what CCT range a light is. Even if it’s off by 10+%, I’m okay with that. It’s more to show if it’s 6500-7000K or 5000-5500K. 


I’m not 100% sure how accurate the CRI measurement is. I just tested another light with an SST70 and got about CRI64… 


That sounds pretty good, I’d be satisfied too.
Mind that light that exits an integrating sphere has some spectrum changes compared to the light that is entered (unless you have a Spectralon coating inside your sphere): slightly more short wave light (the “blues”) are absorbed than longer wave light, so the CCT warms up a bit, it can easily become 500K lower.
ChibiM
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Mike C wrote:
Where did you order it from? Opple home page doesn't seem to take orders, some other sites appear to have it though.

Bought it at Elektrobode.nl (Dutch store), but you can also order it at Amazon.de 

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djozz wrote:
That sounds pretty good, I'd be satisfied too. Mind that light that exits an integrating sphere has some spectrum changes compared to the light that is entered (unless you have a Spectralon coating inside your sphere): slightly more short wave light (the "blues") are absorbed than longer wave light, so the CCT warms up a bit, it can easily become 500K lower.

Hey Djozz, no it's just styrofoam, without a coating. Good to know. I was also thinking about shining it onto/through normal copy paper for testing. Would that help? Or what do you think is the best way to measure CCT?

thefreeman
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With Argyll CMS/x-rite spectrophotometers we can apply a correction for each wavelengths with the spotread command, so first we measure an uniform light source (e.g. an incandescent/halogen bulb), then measure the source in the integrating sphere, then apply the correction. Even with his professional sphere Maukka has to do this.

If you can get the spectrum data then you could apply this correction manually.

ChibiM
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Here are some screen shots from the App

 

 

 

 

Edit: I just created a thread about the Opple to make it easier to find and discuss.: https://budgetlightforum.com/node/79094 

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thefreeman wrote:
With Argyll CMS/x-rite spectrophotometers we can apply a correction for each wavelengths with the spotread command, so first we measure an uniform light source (e.g. an incandescent/halogen bulb), then measure the source in the integrating sphere, then apply the correction. Even with his professional sphere Maukka has to do this.

If you can get the spectrum data then you could apply this correction manually.


Yep, that is the advantage of using a spectrometer to measure light levels. Chibi and me are using a luxmeter in our spheres, so we can not correct for spectrum changes. I had a few lights measured by maukka in his sphere two years ago, with varying tint and CRI, the diffence between his and my calibration varied by as much as 4% for the different lights and I assume that the difference comes from the fact that maukka compensates for spectrum changes and I can not.
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Just curious as someone who has never done this before… is measuring CCT & CRI supposed to be done in a sphere, or are there other/better ways of doing it? I suppose a sphere would help integrate angular differences of certain LEDs (think Cree flip chips with bad tint shift). But is there another way that wouldn’t introduce variation, like the sphere does by absorbing certain wavelengths more than others?

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gchart wrote:
Just curious as someone who has never done this before… is measuring CCT & CRI supposed to be done in a sphere, or are there other/better ways of doing it? I suppose a sphere would help integrate angular differences of certain LEDs (think Cree flip chips with bad tint shift). But is there another way that wouldn’t introduce variation, like the sphere does by absorbing certain wavelengths more than others?

I use my sphere for measuring light output, not for CCT/CRI because I know that it changes the CCT. So if I post CCT/CRI numbers, I always add how/where it is measured (usually the middle of a hotspot from a reflector or a TIR because that is how we mostly use leds).
Maukka can measure integrated CCT/CRI of a led in his sphere because he does the spectrum correction, but he usually also measures in the hotspot of an optic because that has more relevance.
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Depends what you want to measure, if you want to know the tint of the spot then you just shine the flashlight dead on the sensor. If you would want to measure the whole angle profile then you measures at several angle and that tells you how much it varies (see maukka reviews or my thread about LH351D slicing), which is quite important, you might have a nice integrated tint but an absolutely terrible angle profile, as you mentionned somme CREE LEDs are terrible in this aspect, or a 144A might have a terrible egg yolk effect and a nice overall tint.
If you’re measuring a LED bulb, the diffuser averages pretty well already, usually there is very little variation.

Honestly I’m not sure when integrated color measurement is an important metric, I guess for comparing bare LEDs mostly.

Quote:
But is there another way that wouldn’t introduce variation, like the sphere does by absorbing certain wavelengths more than others?

Yes as I and Djozz mentioned, the sphere must be color calibrated, even professional ones.

freeme
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Still saving for a Sekonic Spectomaster meter since last year. cryyell

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CollectEverything
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freeme wrote:

Still saving for a Sekonic Spectomaster meter since last year. cryyell


Dayum that’s a lot of money. I’d probably rather make a firearm purchase for that money. I think a lever-action rifle in .357 magnum would be great fun. Although the price of ammo is greatly inflated right now.

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Collection: TN42, TN40S, Catapult V6, SP36 BLF, sc700d, sc64c LE, D4V2 CuZn, D4V2 CuTi, D4V2 Al x2, KR4 Al x2
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Wishlist: Acebeam K75, Zebralight sc600w mk IV plus, Convoy M3-C
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