Save & earn with MPB; trade-in and buy pre-loved

A matter of degree Kelvin


Time for an update: I still use film, though. Not vast quantities, but I have a darkroom, and I'm not afraid to use it.

I enjoy every image I take: I hope you'll enjoy looking at them.
...Read More

A matter of degree Kelvin

20 May 2021 8:25AM   Views : 676 Unique : 415


There’s a reason that colour in pictures is measured in degrees, but I wonder if you know what it is? Or who Kelvin was that anything’s named after him… This is by way of a lead-in to a routine sort of blog about colour temperature: and the lead image is from my session with AshleyAshton222 yesterday: green curtains, and a lot of trees outside the window mean that AWB might actually have worked well, for once.

Anyway, Kelvin. William Thomson, 1st Baron Kelvin was born in 1824, and was a physicist, particularly interested in thermodynamics, the Third Law of which states that you can never reach absolute zero, the lowest temperature which is possible in the Universe. It’s around 273 degrees below zsero Centigrade, and a temperature scale starting from absolute zero seemed like a good idea: the degrees are the same as the Celsius scale, but start from the bottom. And they’re named after Kelvin.


The missing step is that colour can be defined in terms of the temperature that a perfectly black body needs to be to glow that colour – in practice a piece of iron will do nicely. So red hot, the sort of colour old-fashioned tungsten lamps give, is around 2,000ᵒ Kelvin, and daylight is 6,500ᵒ. This doesn’t take account of the green-magenta dimension that wrecked my portrait of Ashley, but you’ll see it in every editing suite you come across.

What’s this got to do with AWB, you may be asking… Well, it’s the background against which AWB exists, and the idea of AWB is to get accurate colour in any light, although in practice it usually falls short. It seems like a reasonable idea when, for instance, you’re shooting a white plate and want it to look the same in sunlight, lamplight, or shade.


In reality, you don’t necessarily want that sort of fidelity, I’d suggest. For instance, take that sunset view over the lake, with the rosy red tint to the white clapperboard of the boathouse… Do you want that boathouse to be white in your picture, or a delicate pink? Similarly, on a chilly winter’s day, a slight blue tinge conveys the mood of the moment. My solution is to use Daylight balance all the time, unless I see a good and colourful reason to do otherwise…

I know AWB serves many people well – but if subtlety of colouring matters to you, you probably aren’t one of them… And of course you can always adjust things in editing, especially if you shoot RAW files.


Recent blogs by dudler

Focus scales

If you’ve been taking pictures since before autofocus arrived, you’ll be very familiar with focus scales – they are one of the primary controls on an old-school camera, and just one more of the things that you really needed to get right. With autof...

Posted: 27 Dec 2022 7:01AM

Porcelain processing

People commented on the look in my last post and it seems like a good idea to share the secrets for Christmas. I learned the technique several years ago: a model’s boyfriend told me about it, and a website that described it in detail: I tried it, l...

Posted: 23 Dec 2022 10:47AM

You develop your own films don’t you?

If you have your own darkroom, or if you use film cameras regularly, there are always a few people who mention the attic. As in ‘Grandpa’s cameras are in the attic. I don’t even know if they have film in them!’ This leads me to ask if I can have a l...

Posted: 16 Aug 2022 11:17AM

Choose your pond

There’s an old saying about being a big fish and a little pond. Do you want to be the most important person in a small organisation, or are you content being a relatively small cog in a big machine? It’s the same in photography. With relatively mo...

Posted: 3 Jun 2022 2:25PM

Graduated filters

This is for Hannah, and anyone else who has come across the casual way that a lot of togs talk about one or two types of filter that landscaper photographers use a lot: graduated filters and neutral density filters. A graduated filter is one that i...

Posted: 25 Apr 2022 12:18PM


dudler Avatar
dudler Plus
20 2.1k 2048 England
20 May 2021 8:26AM
All - unless something was very odd - shot with Daylight WB.
Chrism8 Avatar
Chrism8 16 1.1k 34 England
20 May 2021 9:04AM
I tend to shoot on a cloudy wb as this suits my style and images and tweak as required in post
Mrserenesunrise Avatar
20 May 2021 9:12AM
I shoot in AWB and RAW so adjust when I edit.
But I will try Daylight AB whilst on holiday next week.
James124 Avatar
James124 Plus
8 81 59 Portugal
20 May 2021 9:36AM
I too use AWB and adjust the raw files if I think it necessary, usually only a tiny tweak is needed.
PS've omitted a rather important " - " before 273 !
thewilliam2 Avatar
thewilliam2 6 1.7k United Kingdom
20 May 2021 10:00AM
One problem with AWB is that every shot has its own unique colour-balance and this can give us a lot more work when we're making up a multi-image frame where the flesh-tones and textile colours need to match.

One wedding photographer colleague does a custom WB for each scene because he needs the colour of the wedding gown colour to be consistent throughout the album and doesn't want to tweak every picture.
pablophotographer Avatar
pablophotographer 12 2.2k 450
20 May 2021 12:37PM
I adjust white balance according to the light source and weather conditions. Sometimes I do not, when I want to achieve a certain look. Do you recall Picasso's blue period? Light blue skin and orange peel can be a fun combination.

The colours our eyes can see are just reflections of light, hence light does play a role on how colours come out.

GGAB Avatar
GGAB 7 31 1 United States
20 May 2021 1:41PM
"Third Law of which states that you can never reach absolute zero, the lowest temperature which is possible in the Universe. It’s around 273 degrees Centigrade". Not to nit pick, however shouldn't this be -273 C?
273C seems kind of warm....Tongue
PaulCox Avatar
20 May 2021 2:51PM
Oh to just have my College days back studying Thermodynamics Degrees Rankin -460 and Degrees Kelvin -273 when in theory everything disappears. Paul.
dudler Avatar
dudler Plus
20 2.1k 2048 England
20 May 2021 2:55PM
James and George - thank you. The price of speed is limited accuracy...

I've duly added 'below zero'! And that's not nit-picking at all - though both temperatures are outside my personal tolerance zome.
dark_lord Avatar
dark_lord Plus
19 3.0k 836 England
20 May 2021 3:46PM
I always shoot with Daylight white balance it's a known point even if I need to tweak or adjust later.
-273.15 C
Temperatures as low as a millionth of degree Kelvin have been achieved in a laboratory.
I took some photos outside in December and to achive neutral colour (so as to be consistent with other shots) Lightroom gave me a setting of 45000 K (yes, three zeros).
Daylight is 5500 K or thereabouts here on Earth (and the moon!) because of our local nuclear fusion reactor. On planets in the Betelgeuse system it's nearer 3000 K, for reference when travel restrictions are relaxed Smile
saltireblue Avatar
saltireblue Plus
13 14.5k 89 Norway
20 May 2021 4:32PM
WB isn't so important for me as I turn virtually everything into b&w...however, on the odd occasion I leave the colour in, I do any adjustments in pp, leaving the camera set to AWB. I always shoot raw.

You must be a member to leave a comment.

ePHOTOzine, the web's friendliest photography community.

Join for free

Upload photos, chat with photographers, win prizes and much more.