Skip to content
Discebo.dk

§ 17

Colour temperature and gel (mired)

Which gel goes on to go from 5600 K to 3200 K?

Answer: When a lamp should match daylight from a window or another lamp, you put correction gel on. The gel's strength is stated in mired, because a shift in kelvin doesn't mean the same thing everywhere on the scale. The calculator converts both colour temperatures to mired, finds the shift and shows what fraction of a full CTO (LEE 204, +159 mired) or a full CTB (LEE 201, −137 mired) that corresponds to. A positive shift makes light warmer, a negative makes it colder.

Formula

Mired = 1.000.000 ÷ farvetemperatur i kelvin

Skift = mired(mål) − mired(lampe): positivt = varmere (CTO), negativt = koldere (CTB)

LEE 204 Full CTO = +159 mired, LEE 205 ½ CTO = +109, LEE 201 Full CTB = −137 (LEE Filters' egne data)

Andel af en fuld gel = skift ÷ gelens mired

Symbols and units in the formula
SymbolMeaningUnit
kilde_kLamp colour temperatureK
maal_kThe colour temperature the light should haveK
=Mired shiftmired
=Share of a full CTO (LEE 204)× fuld CTO
=Share of a full CTB (LEE 201)× fuld CTB
=Lamp miredmired
=Target's miredmired

Validity and source

Source
Mired = 1.000.000 ÷ K; LEE 204 Full CTO = +159, LEE 201 Full CTB = −137 mired (leefilters.com)

Does not apply when

  • Gel steps are not linear: ½ CTO is +109 mired not half of 159. Use ratio instead to choose gel in series closest and check with colour temperature metre or camera white balance. Other brands (Rosco) have slightly different numbers. LED lamps with adjustable colour temperature often need no gel at all.

Worked example

The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.

Substituted

  • Lamp colour temperature5,600 K
  • The colour temperature the light should have3,200 K

Giver

  • Mired shift134 mired
  • Share of a full CTO (LEE 204)0.84 × fuld CTO
  • Share of a full CTB (LEE 201)0.00 × fuld CTB
  • Lamp mired179 mired
  • Target's mired313 mired

Members only

The calculator itself is locked

Create a free user account to unlock all articles, calculators, templates and range — and get access to quizzes and classes. It takes less than a minute: name, email and a password. No payment card.

Create free user →Log in

Want to try something first? See what you can use without an account — the junior zone, the encyclopedia, the videos and more.

Sådan bruger du den

Når lampernes farve skal matche dagslys, tungsten eller en anden lyskilde i scenen, sætter belysningen korrektionsgel på. Beregneren regner farvetemperaturerne om til mired og viser, hvor stor en del af en fuld CTO eller CTB du skal bruge.

Step by step

  1. Find lampens farvetemperatur i databladet, eller mål den med en farvetemperaturmåler.
  2. Bestem den farvetemperatur, lyset skal have, fx dagslyset gennem vinduet.
  3. Mired-skift = 1.000.000 ÷ mål − 1.000.000 ÷ lampe.
  4. Positivt skift = CTO, negativt = CTB. Vælg den gel i rækken, der ligger tættest.

Typical errors

  • At regne i kelvin i stedet for mired. 500 K er ikke det samme skift ved 3000 K som ved 6000 K.
  • At tro at en halv CTO er det halve af en fuld. LEE 205 ½ CTO er +109 mired, ikke +80.
  • At glemme lystabet. En fuld CTB tager ca. et stop.

Examples from everyday life

HMI skal matche tungsten

Et interview er lyst med tungsten på 3200 K, men en HMI på 5600 K skal bruges som baggrundslys og have samme farve.

Lamp colour temperature
5,600 K
The colour temperature the light should have
3,200 K

It means: Skiftet er 134 mired, og det svarer til 0.84 × fuld CTO. En fuld CTO (LEE 204) er det nærmeste valg.

Tungsten skal matche vinduet

En stue lyses med en 3200 K-lampe, men dagslyset fra vinduet er 5600 K, og du vil have lampen til at passe.

Lamp colour temperature
3,200 K
The colour temperature the light should have
5,600 K

It means: Skiftet er -134 mired, og det er 0.98 × fuld CTB. En fuld CTB (LEE 201) dækker det næsten, men den koster ca. et stop lys.

Varmere stemning på dagslyslampe

Du vil gøre en 5600 K-lampe lidt varmere, ned til 4300 K, i en hyggelig scene.

Lamp colour temperature
5,600 K
The colour temperature the light should have
4,300 K

It means: Skiftet er 54 mired, svarende til 0.34 × fuld CTO. Det er en svag korrektion, så vælg en af de svageste CTO'er i rækken og tjek med måleren.

Rule of thumb

5600 K til 3200 K er ca. +134 mired, lidt under en fuld CTO.

How to check the answer

Målets mired − lampens mired skal give skiftet.