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Rosco filters and mired shift value


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#1 Luis Filipe Montanha

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Posted 20 February 2012 - 03:30 PM

Hello,

I follow this forum since 2008, when I went to a film school. I'm now graduated and I have a little project started with two friends of mine. We're working on a film and I am charge of photography department, means, practically everything inside it. We are a little team, we have to raise our effort.

I have two doubts:

1 - What is the big difference between CINEGEL filters and E-COLOUR filters from Rosco? It's only related to the question of the standards? E-colour for Europe?

2 - Why does the same filter (take the example of one HALF-BLUE) produce a variable result in color temperature (increase of 900 degrees for a 3200K and only 600 degrees for a 2600K)?

Thanks for your answers,
I apologize for my rough English.

Luís
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#2 David Mullen ASC

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Posted 20 February 2012 - 03:52 PM

Hello,

I follow this forum since 2008, when I went to a film school. I'm now graduated and I have a little project started with two friends of mine. We're working on a film and I am charge of photography department, means, practically everything inside it. We are a little team, we have to raise our effort.

I have two doubts:

1 - What is the big difference between CINEGEL filters and E-COLOUR filters from Rosco? It's only related to the question of the standards? E-colour for Europe?

2 - Why does the same filter (take the example of one HALF-BLUE) produce a variable result in color temperature (increase of 900 degrees for a 3200K and only 600 degrees for a 2600K)?

Thanks for your answers,
I apologize for my rough English.

Luís



I don't know the answer for the first, but as for the second, increasing or decreasing degrees of Kelvin don't produce even steps of color change, hence why the MIRED system was developed. A 600K shift isn't the same color change amount if starting at 3200K versus 5600K, let's say -- the same shift in Kelvin is more visible at the lower color temp range than in the higher color temp range. You have to work through the MIRED system to figure out how much a gel or filter is changing the color temp.
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#3 Luis Filipe Montanha

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Posted 21 February 2012 - 08:53 PM

I don't know the answer for the first, but as for the second, increasing or decreasing degrees of Kelvin don't produce even steps of color change, hence why the MIRED system was developed. A 600K shift isn't the same color change amount if starting at 3200K versus 5600K, let's say -- the same shift in Kelvin is more visible at the lower color temp range than in the higher color temp range. You have to work through the MIRED system to figure out how much a gel or filter is changing the color temp.


Hello David,

Many thanks for your answer. Quite clear! I don't know if you could help in another thing... Our movie is mainly interiors and I'm searching for some examples, in another movies, to start thinking how I'm gonna conceptualise my cinematography project. Do you have some advice for me?

Thanks for your help!
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#4 Luis Filipe Montanha

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Posted 22 February 2012 - 07:22 AM

Hello again,

Just one more doubt related to the Mired values. Imagine that I have a 4200K source that I want to transform into a 2800K. I've made the calculation and the Mired value is 119. So, for this, I could use a 1/2 CTO and a 1/4 CTO together, to approach the 119 value. But there's a shift of 4 degrees (the two CTO produce a 123 Mired). This could cause some problems?

Thanks for the attention!

Luís
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#5 David Mullen ASC

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Posted 22 February 2012 - 10:15 PM

Hello again,

Just one more doubt related to the Mired values. Imagine that I have a 4200K source that I want to transform into a 2800K. I've made the calculation and the Mired value is 119. So, for this, I could use a 1/2 CTO and a 1/4 CTO together, to approach the 119 value. But there's a shift of 4 degrees (the two CTO produce a 123 Mired). This could cause some problems?

Thanks for the attention!

Luís


It's probably close enough.
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Broadcast Solutions Inc

Metropolis Post

Ritter Battery

Wooden Camera

Abel Cine

rebotnix Technologies

CineTape

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Visual Products

Rig Wheels Passport

Paralinx LLC

FJS International, LLC

Media Blackout - Custom Cables and AKS

Glidecam

The Slider

Tai Audio

Opal