Native color temperature of the sensor

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Felix Steinhardt

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Native color temperature of the sensor

PostWed Oct 17, 2012 7:00 pm

HoHo,

I´m about to buy some more lighting gear and to make the decisions I need to know in which color temp. the sensor works best. Normally, sensors are calibrated to daylight but I just want to be sure.
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Jason Davis

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Re: Native color temperature of the sensor

PostThu Oct 18, 2012 12:48 am

I don't think that it would totally matter especially since it is a native RAW recorder
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Felix Steinhardt

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Re: Native color temperature of the sensor

PostThu Oct 18, 2012 1:32 am

It matters...Sensors have an optimum color temperature where noise is lowest.
For example: If you capture something at 3200 Kelvin on a native 5000 Kelvin sensor you´re gonna underexpose the blue channel pretty hard -> Noisier image.
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Noel Sterrett

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Re: Native color temperature of the sensor

PostFri Oct 19, 2012 11:40 am

Felix Steinhardt wrote:It matters...Sensors have an optimum color temperature where noise is lowest.

Virtually all CMOS sensors are ~daylight balanced. I'd be truly shocked if the BM was not the same.

Cheers.
Admit One Pictures
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Tom

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Re: Native color temperature of the sensor

PostFri Oct 19, 2012 11:50 am

Because of how digital sensors achieve different colour temperatures; applying positive and negative gain to the separate colour channels, the neutral white balance, or native colour temperature is the point at which there is 0 gain on any of the channels.

With Bayer pattern sensors, such as this camera, where green photosites represent 50% of the sensor, the native colour temperature or white balance would almost certainly have a green tint and not be any particular "temperature", so to speak.

Google "uni-wb" or "unified white balance" for a demonstration of how it would look.

So in effect, there would be no native colour temperature in the traditional sense, because the neutral point would not be calibrated for a specific conventional colour temperature.

So the optimum colour temperature of any bayer sensor would result in a green cast image. You can see this also if you convert the dng's to cineform raw and don't carry across the colour temperature meta data.

In any other temperature setting, gain is applied in various measures to each colour channel, which means practically speaking, if you want to film in standard situations, none of the colour temperature settings would be native, whether tungsten, daylight, fluorescent etc. It would be very useful if BMD added to a feature to the camera whereby we could see when an individual colour channel clips, this would help to better expose. Otherwise, allow us to have the neutral temperature selectable from the menu, so that we can see at what point the channels clip before any gain is applied.
Tom Majerski
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http://www.Tracksandlayers.com
Motion Graphics - Colour Grading - VFX
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John Brawley

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Re: Native color temperature of the sensor

PostSun Oct 21, 2012 1:35 am

It's Daylight ish (5000K)

jb
John Brawley ACS
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