Re: CC vs CTO/CTB Filters

E

ectobuilder

Veteran
Re: CC vs CTO/CTB Filters

I'm looking for a color meter that can read Kelvin temperature. From my research, it seems the Sekonic C500 and Gossen models can output the proper color correction filters in terms of CC Filters.

How does this differ from CTO/CTB Filters?

My application would be for cinema rather than for photography.

Also the Gossen model can read kelvin between 2200K - 9300K whereas the Sekonic can read 2300K - 20,000K.

What kinds of sources would have Kelvin readings above 10,000K?
 
If you're going to get one, get a new one. The new ones will be calibrated and also will have an RGB sensor, like a camera would. Many of the old ones will be just RB. Most of the ones on Ebay are either old RB types, have calibration issues, or other troubles. The Kenko KCM 3100 is a great choice as well. Its the continuation of the Minolta Color Meter III which Minolta stopped making and Kenko took over the license for it.
 
Color Meters do a fine job with Sunlight, & tungsten, but are much less accurate with discontinuous light sources, such as HMI, LED, fluorescent, sodium, etc.

With discontinuous light sources a Color Meter is best used to compare similar sources, such as multiple HMIs, but not good at comparing an HMI vs LED, LED vs fluorescent, & so on.
 
Bern Caughey said:
Color Meters do a fine job with Sunlight, & tungsten, but are much less accurate with discontinuous light sources, such as HMI, LED, fluorescent, sodium, etc.

With discontinuous light sources a Color Meter is best used to compare similar sources, such as multiple HMIs, but not good at comparing an HMI vs LED, LED vs fluorescent, & so on.
Click to expand...

Correct, but we do use the Minolta to check HMI lamps before renting them.
 
ectobuilder said:
… the Sekonic C500 and Gossen models can output the proper color correction filters in terms of CC Filters. How does this differ from CTO/CTB Filters?
Click to expand...

The Minolta meters generate readings in Kelvin and CC (Color Compensating) and LB (Light Balancing) scales, and provide an index on the back that correlate the reading to corrective gels. CC corresponds to green/magenta balance, so you would use plus or minus green gels to make CC correction, not CTO or CTB gels. CTO and CTB gels would be used to correct the red/blue balance given by the LB measurements. Use this link for a table that converts color meter CC readings into corresponding plus green and minus green (magenta) gels

Color meters, like the Minolta II & III, are particularly useless with LEDs. The meter makes its calculation of the color temperature based on an assumption that the light source has a continuous spectrum. Because of their unusually discontinuous color spectrum, color readings of LEDs can be severely misleading for both correlated color temperature and green/magenta shift.

Movie Mike
 
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