How to determine ambient color temperature

I feel like I should know this but here's my question. I walk into an indoor room (industrial setting) with my 6D and some LED lights that feature a variable color temperature. How can I determine what the color temperature of the ambient lighting is so I can match it with my LEDs for correct white balance? Can it be done with my camera or do I need some kind of meter or what?

Indoor lighting is 'all over the map' these days!

• In the old days, fluorescents were about half dozen different balances; incandescent in homes was largely 2900K, while photofloods were 3400K.
  
• Now, indoors CFL vary AND LEDS are available in multiple temperatures, and some LED lighting even have user-settable color temperatures! And there can often be 'mixed' lighting in which one part of the room has one and a different part of the room (just a few feet away) can have a very different balance
  

I do understand what you're saying, and I almost always use a gray card in these situations. It's no problem at all if all I'm doing is using the available light. The problem comes in when I need to add light with my LEDs, which I almost always have to do, and I'm just guessing as to how to set the color temp. Mixing color temperatures can be a nightmare. I tried taking a pic using AWB and checking the metadata but all it tells me is that I used AWB. :/

Yes, mixed light can indeed be a nightmare. What I will generally do, when situation permits use of flash, is to deliberately overpower the ambient falling on the subject, but set shutter speed to capture the inherent balance seen in the lighting fixtures, as 'capturing the mood of the setting'

As I said, these days of commonly 'mixed' sources, wherein there is zero thought about selection of bulbs by the owner of the locale, are more of a headache than the 'old days'; industrial setting with different brands and models of fluorescent tubes makes for a real nightmare....ergo, overpower it all.

There are apps for this - here's one, there are others, I've no idea how well they work:

https://www.androidout​.com …/#descripcion_p​rovider_li

Some handheld meters, probably the pricier ones, measure color temp.

tomj wrote in post #19215472
There are apps for this - here's one, there are others, I've no idea how well they work:

https://www.androidout​.com …/#descripcion_p​rovider_li

Some handheld meters, probably the pricier ones, measure color temp.

I have always wondered, in the days of film and the availability of color temperature meters from Minolta and others,, WHAT did anyone DO back then, with that information?!

Supplemental lighting only comes in a small handful of color temperatures so if one is adding light to a scene and you know via a meter what the ambient lighting has for color temp in a mixed lighting situation, what can you do? You cannot 'match' what your supplemental light can output, to the ambient mixed light!

In mixed lighting conditions, shooting RAW is very important. The data in the RAW File is far greater than JPG. That latitude is very very important.

https://www.slrlounge.​com …ce-and-color-temperature/

Ambient color temperature is a contradiction in terms. The light sources themselves—sunlight, skylight, tungsten, flourescent, LED—sport distinct spectrum that do not mix nicely. If hitting your subject from different directions then you have an unsalvageable mess. Even with a uniform source for ambient, the light can bounce off interior surfaces like walls and drapes that will impart their own color cast. All that before you add the key.

Second problem is the definition of color temperature. This term only applies to a black-body radiator where the R/G/B balance falls on a line and, therefore, can be defined by a single number (the color temperature in Kelvin). For all other light sources you must provide two numbers to define the color balance. CIELAB L*a*b* color space is an example where a* and b* are the color component. For color meter, a standard readout will give a nominal color temp and a correction factor in one of the R/G/B channels: this aids preparing a gel pack for your key. Of course, the ambient can screw the result as noted above.

Keep in mind that some light sources are not full spectrum, so you can't necessarily match them. If a source like sodium vapor lights is deficient in red you can't balance it or match it with a full spectrum light. All you can do get close.

gonzogolf wrote in post #19215612
Keep in mind that some light sources are not full spectrum, so you can't necessarily match them. If a source like sodium vapor lights is deficient in red you can't balance it or match it with a full spectrum light. All you can do get close.

...and flicker

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Phil Light wrote in post #19215425
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I feel like I should know this but here's my question. I walk into an indoor room (industrial setting) with my 6D and some LED lights that feature a variable color temperature. How can I determine what the color temperature of the ambient lighting is so I can match it with my LEDs for correct white balance? Can it be done with my camera or do I need some kind of meter or what?.

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I don't know if this is the best way, but it is what I do when shooting outdoor scenes where there is only ambient light. . It works for me in those situations, so perhaps it'll work for you in your situations.

Set your White Balance to K mode and take a guess what you think the WB is and set it to that K setting. . Then take a test pic of the scene you intend to photograph.

Now, hold the camera so you can see the real life scene when you look up, and the LCD screen when you look down. . Look at the test image on the rear LCD. . Look up at the real life scene. . How does the color temperature compare?

Now adjust the K setting so that you can get a test shot closer to the real life scene. . If you had the K set to 6200, and the test image on the LCD looked cooler than the real life scene, then crank the K setting up to 7000. . Now take another test shot and compare the playback on the LCD to the real life scene, just like you did before. . Repeat as many times as you need to, making adjustments until the test image on the LCD looks just like the real life scene.

This is the same thing most of us do when we "chimp" to arrive at the perfect exposure, except we're doing it with color temperature instead of exposure.

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