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Kelvin Temp confusion...
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Aug 1, 2021 16:31:55   #
Racmanaz Loc: In my bedroom why?
 
I thought I had this figured out long ago, but it appears that I do not have a clear understanding on the subject of kelvin temps and the actual color temperature that is presented on photo's. Please help me understand why it's different in these examples. The top image indicates that 3800K is towards the blue tint and the bottom image indicates that 3800K is in the yellow tint range. It's probably something so simple that I am missing. Thanks in advance for all your help to come.


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Aug 1, 2021 16:37:10   #
captivecookie
 
That's a puzzle to me as well. Always thought the hotter the temp, the higher the number. 6500 or around there is supposed to be sunlight, I thought. Perhaps it's a difference between the color temperature of something as opposed to the temp of the light bouncing from something. Though now that I wrote that, isn't that the same thing?

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Aug 1, 2021 16:39:15   #
rmalarz Loc: Tempe, Arizona
 
The hot-or-cold Kelvin temperature scale starts at absolute freezing 0K (-273.15ºC) while the hue-based Kelvin scale relating to color temperature starts with black as the zero point.
--Bob
Racmanaz wrote:
I thought I had this figured out long ago, but it appears that I do not have a clear understanding on the subject of kelvin temps and the actual color temperature that is presented on photo's. Please help me understand why it's different in these examples. The top image indicates that 3800K is towards the blue tint and the bottom image indicates that 3800K is in the yellow tint range. It's probably something so simple that I am missing. Thanks in advance for all your help to come.

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Aug 1, 2021 16:39:52   #
Racmanaz Loc: In my bedroom why?
 
captivecookie wrote:
That's a puzzle to me as well. Always thought the hotter the temp, the higher the number. 6500 or around there is supposed to be sunlight, I thought. Perhaps it's a difference between the color temperature of something as opposed to the temp of the light bouncing from something. Though now that I wrote that, isn't that the same thing?


It's almost confusing as colors of light and colors of paint, if you mix all primary colors of light, you get white and if you mix all primary colors of paint, you get black.

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Aug 1, 2021 16:39:54   #
Orphoto Loc: Oregon
 
On the adobe slider blue side makes your image more blue (compensating for warmer toned light),

The schematic is absolutely correct. Tones corresponding to those temps (black body radiation). If you are in shade with subject lit by open blue sky, manually set for 7 or 8k.

If shooting in raw, adjust to taste later in PP using the slider illustrated.

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Aug 1, 2021 16:49:22   #
David Martin Loc: Cary, NC
 
The white balance slider adjusts color in the opposite direction of the ambient light source. If the image is too orange, it will add blue. If the image is too blue, it will add orange.
Racmanaz wrote:
The top image indicates that 3800K is towards the blue tint
No, it's telling you that if you shoot a photo where ambient light was 3800ºK, say incandescent light, the software will make the correction by adding blue if you correctly set the slider to 3800ºK.
Racmanaz wrote:
and the bottom image indicates that 3800K is in the yellow tint range.
Which is correct.

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Aug 1, 2021 16:57:21   #
BebuLamar
 
Let start with the bottom picture. The higher color temp of the light it's bluer. Now for the first image, for the same light if you tell the raw converter, (or the camera) that the light is redder (low temp) then it would try to make it bluer and thus the slider indicates that if you slide it toward lower number you will get bluer pictures.

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Aug 1, 2021 17:46:47   #
User ID
 
Racmanaz wrote:
I thought I had this figured out long ago, but it appears that I do not have a clear understanding on the subject of kelvin temps and the actual color temperature that is presented on photo's. Please help me understand why it's different in these examples. The top image indicates that 3800K is towards the blue tint and the bottom image indicates that 3800K is in the yellow tint range. It's probably something so simple that I am missing. Thanks in advance for all your help to come.

The first one shows the color of the correction filter for 3800K and the second one shows the color of the light at 3800K. These are by definition opposites.

The first one is most likely based on a scale where no correction filter would be needed at 5600K. The second one is based on the color of pig iron heated to the temperatures seen on the scale.

~~~~~~~~~~~~~~~~~~~~~~~

I think every color hotter than white is an extrapolation to lengthen the scale. I think iron doesn’t actually glow blue. The colors are based on heating a solid or molten material, but at some point the material would likely vaporize. I’m not a physicist so I anticipate hearing from the usual suspects.

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Aug 2, 2021 09:00:37   #
fetzler Loc: North West PA
 
Color Temperature refers to the temperature of a black body radiator. If a body has a temperature above 0K then radiates photons with a defined spectrum. As the temperature of the body increases the peak radiation will move from infrared to red to blue to ultraviolet. The sun is nearly a black body radiator an the surface of the sun is near 5500K. The filament of an incandescent light bulb is also a black body radiator at low voltage the filament glows a dull read (mostly IR radiation) increasing the voltage to normal voltage the light becomes "whiter" and is about the filament has a temperature near 2700K. If we could increase the voltage further without destroying the filament then we would see the filament becoming bluer and finally ultraviolet light would be emitted.

If we set the camera to 2700K and expose a picture in sunlight (5500K) the picture will appear to be blue.
If we set the camera to 5500K and expose a picture by incandescent light (2700K) then the picture will appear orange.

When the camera is set to a lower color temperature than the light source the picture will appear blue.

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Aug 2, 2021 09:12:34   #
Lucian Loc: From Wales, living in Ohio
 
David Martin wrote:
The white balance slider adjusts color in the opposite direction of the ambient light source. If the image is too orange, it will add blue. If the image is too blue, it will add orange.Which is correct.


You nailed it! ...Everybody else should now stand down please.

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Aug 2, 2021 10:23:07   #
Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)
 
Racmanaz wrote:
I thought I had this figured out long ago, but it appears that I do not have a clear understanding on the subject of kelvin temps and the actual color temperature that is presented on photo's. Please help me understand why it's different in these examples. The top image indicates that 3800K is towards the blue tint and the bottom image indicates that 3800K is in the yellow tint range. It's probably something so simple that I am missing. Thanks in advance for all your help to come.


The Kelvin color temperature scale corresponds to the color of a black body being heated. Like iron, it starts off as red, and turns orange, then white then blue where it is at its hottest.

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Aug 2, 2021 10:57:45   #
sippyjug104 Loc: Missouri
 
"White" hot is brighter than "Red" hot. A cool flame, like a match, is yellow whereas from an oxygen acetylene torch it is blue to white. Hence the intensity of heat is related to the color that it emits.

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Aug 2, 2021 11:01:15   #
JBRIII
 
K = C + 273.
Hottest stars are blue giants with temps 30,000 K and higher.

There is some trivia question about only kelvin scale?

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Aug 2, 2021 11:02:04   #
Hip Coyote
 
Oddly, when we say that a picture needs to be "warmer" we make it more orange/yellow, which is actually cooler on the Kelvin temp scale. When something needs to be "cooler" we make it more blue, which is actually hotter on the Kelvin temp scale.

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Aug 2, 2021 12:10:25   #
MrPhotog
 
Racmanaz wrote:

Please help me understand why it's different in these examples. The top image indicates that 3800K is towards the blue tint and the bottom image indicates that 3800K is in the yellow tint range.


Consider it ‘artistic license’ on the part of the designer of that sliding scale, not a scientifically valid representation of light spectrum. If you move the slider to the right ( more yellow) the light temperature number should decrease. Similarly, moving the slider left (more to the blue end) should cause the light temperature to rise.

You are right about daylight being ‘cooler’ than tungsten light—which is rapidly disappearing from the market.

In film days, tungsten-balanced films were available as ‘type A’ (3200 K) and ‘type B’ (3400K). 3800 K is certainly closer to those ‘yellow’ light sources that it is to 5500K ‘daylight’ such as an electronic flash provides.

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