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Photography Question 

Tom Lammert
 

ISO and Color Temp


Using my Canon EOS 20D indoors in low light I raised ISO to 1600 in order to take pictures of my daughter at a shutter speed of 30. I noticed when reviewing the pictures in RAW that to get the best coor I had to shift the color temp all the way to 2800. I suspect that the appropriate color temp was even less. Does using a higher ISO affect color temp and if so how?


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December 28, 2005

 

Jon Close
  No, ISO does not affect the color temperature. Color temp is based on the lighting source only. 2800K is about right for typical tungsten filament light bulbs.


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December 28, 2005

 

Tom Lammert
  Jon, Thank you for the prompt response. Is there a means, other than using flash or other lighting to compensate for lighting that may be below the lowest color temp setting on the camera?


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December 28, 2005

 

robert G. Fately
  Tom, I don't know that you'll come across a light source with a color temperature loser than 2800K.

Understand that the whole color temperature thing relates to physics; it's the expected type of light that would be emitted by a so-called perfect black body at that number of degrees kelvin (Kelvin is like Celcius but 0 degrees K is absolute zero - about -273 degrees C).

Tungsten lighting is very reddish - 3400K is a common light temperature for normal or tungsten halogen type bulbs. As the temperature gets higher, the coor becomes bluer - so noon on a clear day is about 5000K or maybe even 6500K. As you reduce the temperature, though, the color becomes redder - to the point of infrared - thus invisible anyway.

So, unless you want to take IR photos (which some digicams apparently can do) there is no point in compensating for a color temp below 2800 - by then it's IR shooting anyway.


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December 28, 2005

 

Tom Lammert
  Thanks Bob. I might load some images to better explain the color shift that I am getting by lowering the color temperature of the RAW images.


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December 29, 2005

 
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