How to meter kelvin temperature

[Dark Dog]

How do I measure the kelvin temperature of a light? Do I measure the light source? Do I meter the light off of a gray card? Do I meter the light reflecting from the photograph?

 

[24Peter]

How do I measure the kelvin temperature of a light? Do I measure the light source? Do I meter the light off of a gray card? Do I meter the light reflecting from the photograph?

You can use a color meter . I've used light meters but not color meters. I imagine you would measure the light source itself.

But the question is what are you trying to achieve? If you want to set a WB in your camera by matching the color temp you can usually just set a custom WB that will do all that for you. No need to match Kelvin temp. What are you trying to do?

 

[lehill]

How do I measure the kelvin temperature of a light? Do I measure the light source? Do I meter the light off of a gray card? Do I meter the light reflecting from the photograph?

We had a little sub-thread on this topic several months ago when someone believed he received the wrong temperature LED strip lighting. It starts here, but the procedure depends on having the right camera (mine displays Custom White Balance color temp & G/M correction directly), or a raw image and Adobe Camera Raw.

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Lance H

 

[Mark S Abeln]

How do I measure the kelvin temperature of a light? Do I measure the light source? Do I meter the light off of a gray card? Do I meter the light reflecting from the photograph?

You can get an approximate Kelvin reading by photographing a neutral card and then adjusting the white balance off of that in software. The white balance sliders will then give you an approximate color temperature value in Kelvin.

As far as I know, the existence of a "Kelvin" setting in cameras is so that you can simply dial in the kelvin values of your lamps. Most bulbs are sold with a Kelvin color temperature value marked on the packaging. For example, my office lamps are 6500K, and so I would just dial that into the camera. However, it is more accurate and easier just doing a manual white balance.

 

[Dark Dog]

Thank you to those that offer me some answers. I am sorry I was not as clear as I could have been.

Here is what I am working on. I would like to know is how do you measure the light for color correcting photographic images?

Say I have a viewing booth and I would like to check its Kelvin temperature accuracy.

I am using a spot meter.

Do I meter the light source? Do I meter the light reflecting off of a grey card?

Or is there an alternative way I am not aware of?

Thank you

 

[thinkinginimages]

Thank you to those that offer me some answers. I am sorry I was not as clear as I could have been.

Here is what I am working on. I would like to know is how do you measure the light for color correcting photographic images?

Say I have a viewing booth and I would like to check its Kelvin temperature accuracy.

I am using a spot meter.

Do I meter the light source? Do I meter the light reflecting off of a grey card?

Or is there an alternative way I am not aware of?

Thank you

OK, you would need a color meter or other device that can read color temperature. This would typically be an incident reading, but...

A viewing booth is typically set up for 6500k. Often there are switches to change the color temp to various presets.

I'm being a bit vague because of the variables. The bulbs have to be full spectrum. If they are adjustable, they have to be accurate at the alternate settings. The booth is neutral gray/photo white. All of this can be thrown off if there's another calibrated light source nearby, or even the color of your clothing.

https://www.xrite.com/categories/light-booths

There's a lot of interesting theoreticals here. You may judge an image at 6500, and your client is seeing it at 2800, wearing a yellow shirt. It happens.

 

[lehill]

Thank you to those that offer me some answers. I am sorry I was not as clear as I could have been.

Here is what I am working on. I would like to know is how do you measure the light for color correcting photographic images?

Say I have a viewing booth and I would like to check its Kelvin temperature accuracy.

I am using a spot meter.

Do I meter the light source? Do I meter the light reflecting off of a grey card?

Or is there an alternative way I am not aware of?

Thank you

My spot meter can tell me what f-number or shutter speed to set my camera but it doesn't tell me anything about color correction. Exposure settings and color correction are two separate things. It would be pretty cool if your spot meter did both.

I might use my spot meter to determine f-number or shutter speed settings to get the exposure right. Then I would use my camera's custom white balance function with a gray/white card to set my camera to the correct white balance.

--
Lance H

 

[Iliah Borg]

Thank you to those that offer me some answers. I am sorry I was not as clear as I could have been.

Here is what I am working on. I would like to know is how do you measure the light for color correcting photographic images?

Say I have a viewing booth and I would like to check its Kelvin temperature accuracy.

I am using a spot meter.

No practical way to use a spot meter for this purpose.

You need a different device, and those are rather expensive. Try searching e-bay for "X-Rite Spectrophotometer eye", those that are named "i1 pro" or "eye-one pro" would probably be the cheapest options and very useful for the whole colour-managed workflow.

Colour temperature doesn't fully characterize a light source (other than black body radiator), you need to measure the spectrum to see how close the light source is to that black body.

 

[Dark Dog]

Hello Peter,

Thank you for responding to my kelvin temperature question.

What I am doing is measuring the kelvin temperature of my viewing area.

Would I aim my color meter at the light or towards the subject?

The subject in this case would be the photograph.

Thank you

Lloyd Morley