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Brett B

CTO light loss

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Yes, more or less. Full CTO actually is warmer than an 85B filter so it probably loses a little more than 2/3's of a stop, closer to a full stop probably.

 

Full CTO converts 6500K to 3200K (Mired Shift +159).

 

An 85B filter converts 5500K to 3200K (Mired Shift +131). The equivalent gel is Sun 85. You could also try 3/4 CTO, which has a Mired Shift +124.

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Hi,

 

With all due respect to Kodak's manufacturing QC, I'd expect the variance in the filmstock to be more than a mired shift of 7!

 

Phil

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I doubt manufacturing variations would change color temperature balance in a roll of stock since that would mean individual layers would have to be altered. That part of the process is incredibly consistent and automated.

 

However, a very slightly warm or cold image overall is probably within lab processing & printing variations.

 

Trouble is that all of that doesn't solve the issue of color temperature MATCHING of two sources in the same frame, regardless of manufacturing or processing variations, which is why variations in gel colors can matter, although a few MIRED shift points isn't really visible.

 

The other issue is that "daylight" is all over the map in terms of color temperature. This is one reason I don't generally gel windows to tungsten unless I can't really see the view clearly outside, because you end up with this odd color that isn't really 3200K anyway, so now you have to consider gelling your tungsten lights to match the color of the view out the window. Seems less of a problem when the windows are ungelled and you are using HMI's and daylight Kinos inside, and it's easier to gel lights rather than gel windows AND lights to all match. So I generally will only gel a window tungsten if it is very small.

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Yes, more or less. Full CTO actually is warmer than an 85B filter so it probably loses a little more than 2/3's of a stop, closer to a full stop probably.

 

Full CTO converts 6500K to 3200K (Mired Shift +159).

 

An 85B filter converts 5500K to 3200K (Mired Shift +131). The equivalent gel is Sun 85. You could also try 3/4 CTO, which has a Mired Shift +124.

 

 

David,

 

What is the filter number for Full CTO?

 

Is Sun85 filter and 85B filter produces same results? Both are from different manufactures ?

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LEE filters Full CTO is 204. Sun 85 is a Rosco filter. Both are lighting gels. An 85B is a Camera filter.

 

All of this info is available via Google...

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Keep in mind that various warming filters and gels may have the same MIRED shift value in terms of how much they correct the color temperature, but they may have different hues, some more yellow or magenta than others. Besides 85 and 81 camera filters, for example, there are Decamired filters, Coral filters, etc. that people have used for color temperature corrections. They also can vary by how much UV correction they supply in addition.

 

The variations in hues is partly due to manufacturing but also because they are attempting to create a color-correction that matches the particular color response of a film stock. For example the Tiffen fluorescent filters, FL-B and FL-D, are not the same thing exactly as CC Magenta filters because they were designed to correct greenish Cool White fluorescents of the type made in the 1970's for various daylight and tungsten balanced Kodak stocks of the 1970's, probably 16mm color reversal stocks.

 

But to some degree, the exact shade is not so important when you are shooting color negative (or digital) because of the ability to color-correct the image compared to shooting reversal film for direct projection.

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