What is color temp?

[hrtbeat2]

What is color temp and how should you set it?

 

[nibhaz]

What it means....proper setting...don't know!

Color Temperature
Correlated Color Temperature (CCT)
Kelvin
(Term of photometry)

Color temperature is a simplified way to characterize the spectral properties of a light source. While in reality the color of light is determined by how much each point on the spectral curve contributes to its output, the result can still be summarized on a linear scale.

Low color temperature implies warmer (more yellow/red) light while high color temperature implies a colder (more blue) light. Daylight has a rather low color temperature near dawn, and a higher one during the day. Therefore it can be useful to install an electrical lighting system that can supply cooler light to supplement daylight when needed, and fill in with warmer light at night. This also correlates with human feelings towards the warm colors of light coming from candles or an open fireplace at night.

Standard unit for color temperature is Kelvin (K).

(The kelvin unit is the basis of all temperature measurement, starting with 0 K (= -273.16° C) at the absolute zero temperature. The "size" of one kelvin is the same as that of one degree Celsius, and is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water, which positions 0° Celsius at 273.16 K.)

Technically, color temperature refers to the temperature to which one would have to heat a theoretical "black body" source to produce light of the same visual color.

Some typical color temperatures are:

1500 K Candlelight

2680 K 40 W incandescent lamp

3000 K 200 W incandescent lamp

3200 K Sunrise/sunset

3400 K Tungsten lamp

3400 K 1 hour from dusk/dawn

5000-4500 K Xenon lamp/light arc

5500 K Sunny daylight around noon

5500-5600 K Electronic photo flash

6500-7500 K Overcast sky

9000-12000 K Blue sky



this information was cut and paste from: http://www.schorsch.com/kbase/glossary/cct.html

 

[MDS]

Now that we have the technical description of it out of the way, I'll answer what I think was the real question.

As described above 'daylight' actually encompasses a range of color temperatures, but in general 6500K is given as the color temp of daylight. When calibrating your display you want to start with whatever setting is closest to 6500K. For many TVs that is the 'warm' color setting. Warm is a little redder than neutral which is a little redder than 'cool' (or whatever terms your tv uses).

Note also that if want to use a bias light behind the set, those lights should have a color temp of 6500K too.

 

[BMXTRIX]

Now the question is WHY?

Well, many years ago when color came along the industry settled upon 6500K to be the color level that all shows would be balanced to. The cameras and all broadcasting equipment are calibrated to 6500K. What is broadcast is supposed to reflect an accurate reproduction from 6500K calibrated equipment.

So, if you want your TV to properly reproduce what the cameras on the 50 yard line, or on the movie set, were recording - then your TV needs to be set (calibrated) at 6500K as well.

 

[hrtbeat2]

Thanks for the info. So during the day I should have it on HIGH(colder) and nite time LOW(warmer)??

 

[mtrycrafts]

So during the day I should have it on HIGH(colder) and nite time LOW(warmer)??

No!!! Once your TV is calibrated to 6500K, it stays there.
I am sure the examples were given to show how daylight color changes during the day. That doesn't mean you change the calibration as then it would have no meaning.
Just as the length of a meter is fixed, so is the calibration of the TV

 

[BMXTRIX]

If you ever pick up an issue of Home Theater magazine, you will see 'pre-calibration' and 'post calibration' tables for color balance. The post calibration levels are always trying to achieve a flat line across 6500K and usually (usually!) they are pretty close. The closer a display gets to a flat 6500K color temperature across the board, the more points it will receive.

Not the Home Theater ever gives 'bad' reviews, but at least there is some usable data there to be aware of.

 

[Shadow_Ferret]

I'm curious about the second part of the poster's question. "How does one set it?"

I don't think that was really answered. Can we set it ourselves? Or do we need a tech to come in and calibrate things?

 

[BMXTRIX]

A color temperature metering tool is necessary. A quick Google search provided me this:

http://www.svconline.com/mag/avinstall_different/

I would expect an ISF calibration technician would carry a good ($1,000+) color temp meter.

It is definitely possible for ANYONE to do this... as long as you have the right tools and proper training. So, really, very few people actually know how to do this.

Tools like Avia & Video Essentials DVDs definitely go a long way to making setup of a display much better than nothing. But, it isn't ISF calibrated either.