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

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.

Yeh, forgot who, though.

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.

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.

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

Copied from a previous comment of mine :

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 : Zebralight SC64c LE with LH351D NOT high CRI - #105 by Noir
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.

I just ordered the Opple Light Master III

Let's see how well it works.

congratulations :+1:

I look forward to your impressions

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

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

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.

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.

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...

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

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.

Bought it at (Dutch store), but you can also order it at

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?

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.

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.:

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.

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?